EP3515594A1

EP3515594A1 - Method for providing a fixed catalyst bed containing a doped structured shaped catalyst body

Info

Publication number: EP3515594A1
Application number: EP17764838.3A
Authority: EP
Inventors: Rolf Pinkos; Michael Schreiber; Zeljko KOTANJAC; Michael Nilles; Irene DE WISPELAERE; Michael Schwarz; Marie Katrin Schroeter
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2016-09-23
Filing date: 2017-09-13
Publication date: 2019-07-31
Also published as: WO2018054740A1; SG11201901336RA; CN109789400A; KR20190058486A; US20190344248A1; JP2019530570A

Abstract

The invention relates to a novel method for providing a fixed catalyst bed which contains a doped structured shaped catalyst body, a reactor which contains a fixed catalyst bed of said type in a fixed built-in form and to the use of the thus obtained fixed catalyst bed and reactors for hydrogenation reactions.

Description

A method of providing a fixed catalyst bed containing doped structured structured catalyst bodies

BACKGROUND OF THE INVENTION

The present invention relates to a novel process for providing a fixed catalyst bed containing doped structured structured catalyst bodies, a reactor containing such a fixed catalyst bed in a stationary built-in form, and the use of the fixed catalyst beds and hydrogenation reaction reactors thus obtained.

STATE OF THE ART

Raney metal catalysts are highly active catalysts that have found wide commercial use, especially for the hydrogenation of mono- or polyunsaturated organic compounds. Typically, Raney catalysts are alloys containing at least one catalytically active metal and at least one alkali-soluble (leachable) alloy component. Typical catalytically active metals are, for example, Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and typical leachable alloy components are e.g. Al, Zn and Si. Such Raney metal catalysts and methods for their preparation are known e.g. in US Pat. No. 1,628,190,

US 1,915,473 and US 1,563,587. Prior to their use in heterogeneously catalyzed chemical reactions, especially in a hydrogenation reaction, Raney metal alloys generally require activation. Conventional methods for activating Raney metal catalysts include grinding the alloy into a fine powder if it is not already powdered by the prior art. For activation, the powder is subjected to treatment with an aqueous liquor, wherein the leachable metal is partially removed from the alloy and the highly active non-leachable metal remains. The powders thus activated are pyrophoric and are usually stored under water or organic solvents in order to avoid contact with oxygen and the associated deactivation of the Raney metal catalysts.

According to a known method for activating suspended Raney nickel catalysts, a nickel-aluminum alloy with 15 to 20 wt .-% strength sodium hydroxide solution is treated at temperatures of 100 ° C or higher. In US 2,948,687 it is described to prepare a Raney nickel molybdenum catalyst from a milled Ni-Mo-Al alloy having particle sizes in the range of 80 mesh (about 0.177 mm) or finer by first placing the alloy at 50 ° C with Treated 20% wt .-% NaOH solution and the temperature to 100 to 1 15 ° C raises.

A significant disadvantage of powdered Raney metal catalysts is the need to separate them from the reaction medium of the catalyzed reaction by expensive sedimentation and / or filtration processes.

It is known to use Raney metal catalysts in the form of larger particles. Thus, US Pat. No. 3,448,060 describes the preparation of structured Raney metal catalysts, wherein in a first embodiment an inert carrier material is coated with an aqueous suspension of a pulverulent nickel-aluminum alloy and freshly precipitated aluminum hydroxide. The resulting structure is dried, heated and contacted with water, releasing hydrogen. Subsequently, the structure is hardened. Optionally, leaching with an alkali hydroxide solution is provided. In a second embodiment, an aqueous suspension of a powdered nickel-aluminum alloy and freshly precipitated aluminum hydroxide is subjected to shaping without the use of a carrier material. The structure thus obtained is activated analogously to the first embodiment. Other suitable for use in fixed bed catalysts Raney metal catalysts may have hollow bodies or spheres or otherwise supported. Such catalysts are z. In EP 0 842 699, EP 1 068 900, US 6,747,180,

US 2,895,819 and US 2009/0018366. US 2,950,260 describes a method for activating a catalyst of a granular nickel-aluminum alloy by treatment with an aqueous alkali solution. Typical particle sizes of this granular alloy range from 1 to 14 mesh (about 20 to 1.4 mm). It has been found that contacting a Raney metal alloy, such as a Ni-Al alloy, with an aqueous liquor results in an exothermic reaction to produce larger amounts of hydrogen. The following reaction equations are intended to illustrate, by way of example, possible reactions which take place when a Ni-Al alloy is brought into contact with an aqueous alkali metal hydroxide, such as NaOH:

2 NaOH + 2 AI + 2 H ₂ 0 -> 2 NaAI0 ₂ + 3 H ₂

2 Al + 6 H ₂ O -> 2 Al (OH) ₃ + 3 H ₂

2 Al (OH) ₃ - Al ₂ O ₃ + 3 H ₂ O US 2,950,260 has for its object to provide an activated granular hydrogenation catalyst of a Ni-Al alloy with improved activity and lifetime available. For this purpose, the activation is carried out with a 0.5 to 5 wt .-% strength NaOH or KOH, wherein the temperature is maintained by cooling to below 35 ° C and the contact time is chosen so that not more than 1, 5 parts H2 mole per mole equivalent Leach are liberated. In contrast to a powdery, suspended catalyst, the treatment of granular Raney metal catalysts removes a significantly lower proportion of aluminum from the structure. This is in a range of only 5 to 30 wt .-%, based on the amount of aluminum originally present. Catalyst particles having a porous activated nickel surface and an unchanged metal core are obtained. A disadvantage of the catalysts thus obtained, in which only the outermost layer of the particles is catalytically active, is their sensitivity to mechanical stress or abrasion, which can lead to a rapid deactivation of the catalyst. The teaching of US Pat. No. 2,950,260 is restricted to granular shaped catalyst bodies which fundamentally differ from larger structured shaped bodies. Moreover, this document also does not teach that the catalysts may contain promoter elements in addition to nickel and aluminum. It is known to subject hydrogenation catalysts, such as Raney metal catalysts, a doping with at least one promoter element in order, for. B. to achieve an improvement in the yield, selectivity and / or activity in the hydrogenation. Thus, as a rule, products of improved quality can be obtained. Such dopants are disclosed in US 2,953,604, US 2,953,605, US 2,967,893, US Pat.

US 2,950,326, US 4,885,410 and US 4,153,578.

The use of promoter elements serves, for example, unwanted side reactions such. B. isomerization reactions to avoid. Promoter elements are also suitable to modify the activity of the hydrogenation catalyst to z. B. in the hydrogenation of starting materials with several hydrogenatable groups to achieve either a targeted partial hydrogenation of a particular group or more specific groups or a complete hydrogenation of all hydrogenatable groups. So z. For example, it is known to use a copper-modified nickel or palladium catalyst for the partial hydrogenation of 1,4-butynediol to 1,4-butenediol (see, for example, US Pat.

GB 832141). In principle, the activity and / or the selectivity of a catalyst can thus be increased or decreased by doping with at least one promoter metal. Such doping should not adversely affect the other properties of the doped catalyst as far as possible. For the modification of shaped catalyst bodies by doping, the following four methods are known in principle:

The promoter elements are already present in the alloy for producing the shaped catalyst bodies (method 1),

the shaped catalyst bodies are brought into contact with a dopant during activation (method 2),

the shaped catalyst bodies are brought into contact after activation with a dopant (Method 3),

the shaped catalyst bodies are brought into contact with a dopant in the hydrogenation feed stream during hydrogenation, or a dopant is otherwise introduced into the reactor during hydrogenation (Method 4).

The above-mentioned method 1, in which at least one promoter element is already contained in the alloy for the preparation of the shaped catalyst body is z. B. in the already mentioned US 2,948,687 described. Thereafter, a finely ground nickel-aluminum-molybdenum alloy is used for catalyst preparation to produce a molybdenum-containing Raney nickel catalyst. The above methods 2 and 3 are z. Example in US 2010/01741 16 A1

(= US 8,889.91 1) described. Thereafter, a doped catalyst from a

Ni / Al alloy, which is modified during and / or after its activation with at least one promoter metal. In this case, the catalyst can optionally be subjected to a first doping before activation. The promoter element used for doping by absorption on the surface of the catalyst during and / or after activation is selected from Mg, Ca, Ba, Ti, Zr, Ce, Nb, Cr, Mo, W, Mn, Re, Fe, Co, Ir, Ni, Cu, Ag, Au, Bi, Rh and Ru. If the catalyst precursor is already subjected to doping before activation, the promoter element is selected from Ti, Ce, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Pd, Pt and Bi ,

The above method 3 is also described in GB 2104794. This document relates to Raney nickel catalysts for the reduction of organic compounds, especially the reduction of carbonyl compounds and the production of butanediol from butynediol. To prepare these catalysts, a Raney nickel catalyst is subjected to a doping with a molybdenum compound, which may be solid, as a dispersion or as a solution. Other promoter elements, such as Cu, Cr, Co, W, Zr, Pt or Pd may additionally be used. In one specific embodiment, an already activated commercially available undoped Raney nickel Catalyst suspended in water together with ammonium molybdate and the suspension stirred until a sufficient amount of molybdenum was added. In this document only particulate Raney nickel catalysts are used for doping, especially the use of structured shaped bodies is not described. There is also no indication as to how the catalysts in the form of a structured fixed catalyst bed can be introduced into a reactor and how the catalyst fixed bed introduced into the reactor can then be activated and doped. The above method 4, z. As described in US 2,967,893 or US 2,950,326. Thereafter, copper in the form of copper salts is added to a nickel catalyst for the hydrogenation of 1,4-butynediol in the aqueous.

According to EP 2 486 976 A1, supported activated Raney metal catalysts are subsequently doped with an aqueous metal salt solution. Specifically, as the carrier, the usual bulk materials are used, such. B. SiO 2 -coated glass body with a diameter of about 3 mm. It is not described to carry out the doping and optionally already the activation on a stationary fixed catalyst bed of structured catalyst bodies in a reactor. Thus, with the process described in this document, it is impossible to provide a fixed catalyst bed which has a gradient in the concentration of promoter elements in the direction of flow of the reaction medium of the reaction to be catalyzed.

EP 2 764 916 A1 describes a process for the preparation of foam-like catalyst shaped bodies which are suitable for hydrogenations, in which: a) a metal foam molding is provided which contains at least one first metal, which is selected, for example, from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, b) applying to the surface of the metal foam molded body at least a second leachable component or a component convertible by alloy into a leachable component selected, for example, from Al, Zn and Si , and c) forming an alloy by alloying the metal foam molding obtained in step b) at least on a part of the surface, and d) subjecting the foam-like alloy obtained in step c) to a treatment with an agent capable of leaching the leachable components of the alloy. This document teaches to use for the step d) a 1 to 10 molar, ie 4 to 40% by weight aqueous NaOH. The temperature in step d) is 20 to 98 ° C, and the treatment time is 1 to 15 minutes. It is quite generally mentioned that the foam-like shaped bodies according to the invention can also be formed in situ in a chemical reactor, although any concrete details are missing. EP 2 764 916 A1 further teaches that promoter elements can be used in the preparation of foam-like shaped catalyst bodies. The doping can be carried out together with the application of the leachable component on the surface of the previously prepared metal foam molding. The doping can also take place in a separate step following the activation.

EP 2 764 916 A1 does not contain the slightest information on the dimension of the chemical reactors for the use of the foam-shaped moldings, the type, amount and dimensioning of the moldings introduced into the reactor and for introducing the moldings into the reactor. In particular, there is no indication as to how a fixed catalyst bed actually located in a chemical reactor can first be activated and then doped.

It has been found that the type of doping and also the type of prior activation of fixed catalyst beds of immobilized structured shaped bodies and especially of foam-shaped moldings is critical for the performance properties of the resulting fixed catalyst beds. It is especially critical that both the freshly formed Raney metal and the applied promoter elements remain bound within or on the surface of the moldings and do not escape. The loss of the activated catalyst metal results in significantly less catalytically active sites in the catalyst structure of the fixed bed catalyst. During activation with aqueous alkali, the Raney metal can be discharged from the structure. In the worst case, the Raney metal is even found in the later hydrogenation product. Due to the loss of the promoter elements, the effect sought with the doping, for. As an increase in the selectivity of a particular hydrogenation product can be significantly reduced.

It is an object of the present invention to provide an improved process for the doping of fixed catalyst beds which overcomes as many of the aforementioned disadvantages as possible. Surprisingly, it has now been found that fixed catalyst beds can be obtained from structured shaped catalyst bodies having very good performance properties by first subjecting a fixed catalyst bed made of immobilized, structured shaped catalyst bodies to activation of a treatment with an aqueous base and obtaining this after activation Fixed catalyst bed brings into contact with a dopant. This form of activation is particularly suitable for fixed catalyst beds in reactors for hydrogenation reactions on an industrial scale.

It has furthermore been found that the activated and doped fixed catalyst beds obtained by the process according to the invention are distinguished by high mechanical stability and long service lives. In particular, it has been found that highly active Raney metal catalysts are obtained in the form of fixed catalyst beds when the concentration of the aqueous base used for activation is kept within a not too high range and the temperature gradient in the fixed catalyst bed resulting from activation does not reach an upper limit exceeds. It has furthermore been found that the fixed catalyst beds obtained by the process according to the invention are distinguished by a high selectivity with respect to the desired hydrogenation product, depending on the promoter elements used. The loss of promoter elements when using the catalysts for hydrogenation is very low. It has also been found that even if there is a long-term wear or removal of the outer layers of the active doped catalyst species, the original activity can be restored by the doping process according to the invention is carried out again.

It has furthermore been found that it is possible with the method according to the invention to provide fixed catalyst beds which contain the promoter elements heterogeneously distributed with respect to their concentration. Specifically, the catalyst fixed bed obtained by the process of the present invention has a gradient in the flow direction with respect to the concentration of the promoter elements. It has now surprisingly been found that in the hydrogenation of 1, 4-butynediol to obtain

1, 4-butanediol a particularly high selectivity is achieved when using a fixed catalyst bed of Ni / Al catalyst moldings doped with Mo and wherein the concentration of molybdenum in the flow direction of the reaction medium of the hydrogenation reaction increases. It was also surprisingly found that in the hydrogenation of 4-butyraldehyde to give n-butanol a particularly high selec- tivity is achieved when using a fixed catalyst bed of Ni / Al catalyst moldings, which are doped with Mo and wherein the concentration of molybdenum decreases in the flow direction of the reaction medium of the hydrogenation reaction. SUMMARY OF THE INVENTION

A first aspect of the invention is a process for providing a fixed catalyst bed containing monolithic shaped catalyst bodies or consisting of monolithic shaped catalyst bodies containing at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and containing at least one second component which is selected from Al, Zn and Si, wherein subjecting the fixed catalyst bed to activate a treatment with a maximum of 3.5% by weight aqueous base and subjected to the catalyst fixed bed obtained after activation with contacting a dopant having at least one promoter element different from the first metal and the second component.

In a further preferred embodiment, the catalyst fixed bed during activation has a temperature gradient, wherein the temperature difference between see the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed is maintained at a maximum of 50 K.

In a further preferred embodiment, the catalyst fixed bed after activation and before being contacted with a dopant is subjected to a treatment with a washing medium selected from water, C 1 -C 4 -alkanols and mixtures thereof.

In a further preferred embodiment, the doping medium contains Mo as a promoter element, especially Mo as the sole promoter element.

In a further preferred embodiment, the fixed catalyst bed has a gradient with respect to the concentration of the promoter elements in the direction of flow of the reaction medium of the reaction to be catalyzed. A special subject of the invention is a process for providing a fixed catalyst bed comprising: a) introducing into a reactor a fixed bed of catalyst containing monolithic shaped catalyst bodies or monolithic shaped catalyst bodies contain at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and containing at least one second component selected from Al, Zn and Si, b) the fixed catalyst bed c) optionally subjecting the activated fixed catalyst bed obtained in step b) to a treatment with a washing medium which is selected from water, C 1 -C 4 -alkanols and mixtures thereof, d) the catalyst fixed bed obtained after the activation in step b) or after the treatment in step c) is brought into contact with a dopant which has at least one element selected from the first metal and the second component of the step a ) is used different shaped catalyst bodies.

A more specific object of the invention is a method of providing

Catalyst fixed bed, in which one introduces a fixed catalyst bed in a reactor containing monolithic shaped catalyst body or consists of monolithic catalyst form bodies containing at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and the at least one second component selected from Al, Zn and Si, the catalyst fixed bed for activating a treatment with a maximum of 3.5 wt .-% aqueous base is subjected, wherein the base is selected from alkali metal hydroxides, alkaline earth metal and mixtures thereof, and wherein the fixed catalyst bed has a temperature gradient and the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed is maintained at a maximum of 50K, subjecting the activated fixed catalyst bed obtained in step b) to a treatment with a wash medium selected from is under water he C1-C4 alkanols and mixtures thereof which, after the treatment in step c), brings the fixed catalyst bed into contact with a dopant containing at least one promoter element is selected from Ti, Ta, Zr, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Ce and Bi.

Another object of the invention is a reactor containing a fixed catalyst bed, which is obtainable by a method as defined above and below.

Another object of the invention is a process for the hydrogenation of hydrogenatable organic compounds, in particular organic compounds having at least one carbon-carbon double bond, carbon-nitrogen double bond, carbon-oxygen double bond, carbon-carbon triple bond, carbon-nitrogen Triple bond or nitrogen-oxygen double bond, in the presence of an activated fixed catalyst bed, obtainable by a process as defined above and hereinafter, or in a reactor as defined above and below.

EMBODIMENTS OF THE INVENTION

The invention comprises the following preferred embodiments: A process for providing a fixed catalyst bed containing monolithic shaped catalyst bodies or consists of monolithic shaped catalyst bodies containing at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and the at least one second Component, which is selected from Al, Zn and Si, wherein subjecting the fixed catalyst bed to the activation of a treatment with a maximum of 3.5 wt .-% aqueous base and brings the obtained after activation catalyst fixed bed with a dopant in the at least one promoter element different from the first metal and the second component. 2. Process according to embodiment 1, in which a) a fixed catalyst bed is introduced into a reactor which contains monolithic shaped catalyst bodies or consists of monolithic shaped catalyst bodies which contain at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and the at least one second

Component which is selected from Al, Zn and Si, b) subjecting the fixed catalyst bed to the activation of a treatment with a maximum of 3.5% by weight aqueous base, c) optionally subjecting the activated fixed catalyst bed obtained in step b) to a treatment with a washing medium which is selected from water, C 1 -C 4 alkanols and mixtures thereof, d) after activation in step b) or after the treatment in step c ) is contacted with a dopant having at least one element which is different from the first metal and the second component of the catalyst bodies used in step a).

3. Process according to embodiment 2, wherein the reactor has an internal volume in the range from 0.1 to 100 m ³ , preferably from 0.5 to 80 m ³ . 4. The method according to any one of the preceding embodiments, wherein the fixed catalyst bed in the flow direction has a gradient with respect to the concentration of the promoter elements.

5. The method according to any one of the preceding embodiments, wherein the used monolithic catalyst form body, based on the entire shaped body, a smallest dimension in a direction of at least 1 cm, preferably at least 2 cm, in particular at least 5 cm.

6. The method according to any one of the preceding embodiments, wherein the fixed catalyst bed for activating a treatment with a maximum of 3.5 wt.

% aqueous base, preferably the catalyst fixed bed for activating a treatment with a 0.5 to 3.5 wt .-% aqueous base subjects. 7. The method according to any one of the preceding embodiments, wherein the base is selected from NaOH, KOH and mixtures thereof.

8. Method according to one of the preceding embodiments, wherein the fixed catalyst bed during the activation has a temperature gradient and the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed at a maximum of 50 K, preferably at a maximum of 40 K, in particular at a maximum of 25 K, is held. Method according to one of the preceding embodiments, wherein for activation, a stream of the maximum 3.5 wt .-% aqueous base passes through the fixed catalyst bed.

Method according to one of the preceding embodiments, wherein the maximum of 3.5 wt .-% aqueous base used for activation is at least partially conducted in a liquid circulation stream.

The process of embodiment 10, wherein in addition to the base carried in the liquid recycle stream, fresh aqueous base is added to the fixed catalyst bed.

A process according to any of embodiments 10 or 11, wherein the ratio of aqueous base carried in the recycle stream to freshly added aqueous base is in the range of from 1: 1 to 1000: 1, preferably from 2: 1 to 500: 1, especially 5: 1 to 200: 1. Method according to one of the preceding embodiments, wherein the flow rate of the aqueous base through the reactor containing the fixed catalyst bed in a range of 0.5 m / h to 100 m / h. Method according to one of the preceding embodiments, wherein the loaded aqueous base obtained during the activation is at least partially removed. Method according to one of the preceding embodiments, wherein from the activation a discharge of laden aqueous base is removed and subjected to a gas / liquid separation, whereby a hydrogen-containing gas phase and a liquid phase are obtained. Method according to embodiment 15, wherein the liquid phase is at least partially recycled as a liquid partial stream in the activation.

Method according to one of the preceding embodiments, wherein the monolithic shaped catalyst bodies are in the form of a foam.

Method according to one of the preceding embodiments, wherein to provide the monolithic shaped catalyst bodies: a1) provides a metal foam molded body containing at least a first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd on which surface of the metal foam molded body applies at least a second component, which contains an element which is selected from Al, Zn and Si, and a3) forms an alloy by alloying the metal foam molding obtained in step a2) at least on a part of the surface.

Method according to one of the preceding embodiments, wherein the first metal contains Ni or consists of Ni. Method according to one of the preceding embodiments, wherein the second component contains Al or consists of Al. Method according to one of embodiments 2 to 20, wherein the washing medium used in step c) contains water or consists of water.

Method according to one of embodiments 2 to 21, wherein the treatment with the washing medium is carried out in step c) until the running washing medium has a conductivity at 20 ° C of at most 200 mS / cm, preferably at most 100 mS / cm, in particular at most 10 mS / cm.

Method according to one of embodiments 2 to 22, wherein in step c) water is used as the washing medium and the treatment is carried out with the washing medium until the effluent washing medium has a pH at 20 ° C of at most 9, more preferably of at most 8, in particular of at most 7. Method according to one of the preceding embodiments, wherein the dopant contains at least one promoter element selected from Ti, Ta, Zr, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd , Pt, Cu, Ag, Au, Ce and Bi, preferably Ti, Ce, V, Mo, W, Mn, Re, Ru, Rh, Ir, Pt and Bi.

Method according to one of the preceding embodiments, wherein the dopant contains Mo as a promoter element, preferably Mo contains as a single promoter element. 26. The method according to any one of the preceding embodiments, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of shaped catalyst bodies which contain nickel and aluminum and which are doped with Mo and wherein the fixed catalyst bed in the flow direction has a gradient with respect to the Mo concentration.

A reactor containing a fixed catalyst bed obtainable by a process as defined in any one of claims 1 to 26. 28. A process for the hydrogenation of hydrogenatable organic compounds, in particular organic compounds containing at least one carbon-carbon double bond, carbon-nitrogen double bond, carbon-oxygen double bond, carbon-carbon triple bond, carbon-nitrogen triple bond or nitrogen Oxygen double bond, in the presence of an activated fixed catalyst bed, obtainable by a process as defined in any one of claims 1 to 26, or in a reactor as defined in claim 27.

29. Process according to embodiment 28 for the hydrogenation of 1,4-butynediol to give 1,4-butanediol or for the hydrogenation of 4-butyraldehyde to give n-butanol.

30. Process according to embodiment 28 or 29 for the hydrogenation of 1,4-butynediol to give 1,4-butanediol, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of catalyst form bodies which contain nickel and aluminum and which are doped with Mo and wherein the concentration of molybdenum in the flow direction of the reaction medium of the hydrogenation reaction increases.

31. A process according to embodiment 28 or 29 for the hydrogenation of 4-butyraldehyde to give n-butanol, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of catalyst form bodies containing nickel and aluminum doped with Mo and wherein the concentration of molybdenum in the flow direction of the Reaction medium of the hydrogenation reaction decreases. 32. The method according to any one of embodiments 28 to 31, wherein the hydrogenation is carried out according to the inventive method in the presence of CO.

33. The process of embodiment 32, wherein during the hydrogenation, the CO content in the gaseous phase within the reactor is in a range of 0.1 to 10000 ppm by volume, preferably in a range of 0.15 and 5000 ppm by volume, in particular in a range of 0.2 to 1000 ppm by volume.

DESCRIPTION OF THE INVENTION

Providing the fixed catalyst bed (also referred to as step a))

In the context of the invention, a fixed catalyst bed is understood to be a device incorporated in a reactor which is stationary (immobilized) during the activation according to the invention, the subsequent doping and the subsequent hydrogenation and which comprises one or preferably several monolithic shaped catalyst bodies. The introduction of the fixed catalyst bed into the reactor takes place by fixed installation of the monolithic shaped catalyst bodies. The resulting fixed catalyst bed has a plurality of channels through which the liquid treatment medium (i.e., aqueous base) used for activation, the dopant, if used, the wash medium, and the reaction mixture of the heterogeneously catalyzed hydrogenation can be flowed through.

To produce a suitable fixed catalyst bed, the monolithic catalyst shaped bodies can be installed side by side and / or one above the other in the interior of the reactor. Processes for incorporation of catalyst form bodies are known in principle to the person skilled in the art. Thus, for example, one or more layers of a foam-like catalyst can be introduced into the reactor. Monoliths, each consisting of a ceramic block, can be stacked next to and above each other in the interior of the reactor. In this case, it is generally necessary to ensure that the liquid treatment medium and the reaction mixture of the catalyzed reaction flow exclusively or essentially through the shaped catalyst bodies and not past them. In order to ensure a bypass-free flow as possible, the monolithic shaped catalyst bodies can be sealed against each other and / or to the inner wall of the reactor by means of suitable devices. These include z. As sealing rings, sealing mats, etc., which consist of an inert material under the treatment and reaction conditions.

The shaped catalyst bodies are preferably incorporated into the reactor in one or more essentially horizontal layers with channels, which make it possible to flow through the catalyst bed in the flow direction of the aqueous base used for activation and of the reaction mixture of the catalyzed reaction. Preferably, the installation is carried out in such a way that the fixed catalyst bed fills the reactor cross-section as completely as possible. If desired, the fixed catalyst bed can also be further Built-in components, such as power distributors, devices for feeding gaseous or liquid reactants, measuring elements, in particular for a temperature measurement, or inert packs. The processes according to the invention are suitable in principle for pressure-resistant reactors, as are usually used for exothermic, heterogeneous reactions with the introduction of a gaseous and a liquid educt and especially for hydrogenation reactions. These include the commonly used reactors for gas-liquid reactions, such. B. tube reactors, tube bundle reactors and gas circulation reactors. A special embodiment of the tube reactors are shaft reactors. Such reactors are known in principle to the person skilled in the art. In particular, a cylindrical reactor with a vertical longitudinal axis is used, which has at the bottom or top of the reactor one or more inlet devices for feeding a starting material mixture containing at least one gaseous and at least one liquid component. If desired, partial streams of the gaseous and / or liquid starting material can additionally be fed to the reactor via at least one further feed device. The hydrogenation reaction mixture is generally present in the reactor in the form of a two-phase mixture having a liquid and a gaseous phase. It is also possible that in addition to the gas phase two liquid phases are present, for. B. if more components are present in the hydrogenation.

The heat of reaction released during the activation of the fixed catalyst bed or during the hydrogenation can be at least partially removed by active cooling. This can be done by indirect heat exchange by means of inside or outside the reactor mounted heat exchanger through which a coolant is passed. This is one way to keep the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed below the maximum value. The coolant used can be customary liquids or gases. Preferably, the coolant used is water, for example softened and degassed water (so-called boiler feed water).

On the other hand, the heat of reaction liberated in the activation of the fixed catalyst bed or in the hydrogenation can be at least partially removed by passive cooling. In this embodiment, no heat is removed from the reactor by active cooling, but transferred to the treatment medium, so that, so to speak, an adiabatic way of driving is realized. In this case, the heating of the liquid reaction mixture must be limited so that the maximum temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the catalyst fixed bed and the desired maximum temperature is not exceeded during activation. This can be z. B. via the flow rate of the aqueous base through the fixed catalyst bed and the concentration of the aqueous base used.

The processes according to the invention are particularly suitable for the activation of fixed catalyst beds for hydrogenation reactions which are to be carried out on an industrial scale. The reactor then preferably has an internal volume in the range from 0.1 to 100 m ³ , preferably from 0.5 to 80 m ³ . The term internal volume refers to the volume including the fixed catalyst beds present in the reactor and optionally further existing internals. Of course, the technical advantages associated with the activation and doping according to the invention are also already apparent in reactors with a smaller internal volume. In the process according to the invention "monolithic" shaped catalyst bodies are used. Monolithic shaped bodies in the sense of the invention are structured shaped bodies which are suitable for the production of immobilized, structured fixed catalyst beds. In contrast to particulate catalysts, it is possible to produce fixed monolithic beds from monolithic shaped bodies which are substantially coherent and seamless. This corresponds to the definition of monolithic in the sense of "consisting of one piece". The monolithic shaped catalyst bodies according to the invention are characterized, in contrast to catalyst beds, for. B. from pellets, often by a higher ratio of axial flow (longitudinal flow) over radial flow (cross-flow) from. Monolithic shaped catalyst bodies accordingly have channels in the flow direction of the reaction medium of the hydrogenation reaction. Particulate catalysts usually have the catalytically active sites on an external surface. Catalyst fixed beds of monolithic moldings have a plurality of channels, wherein the catalytically active sites are arranged on the surface of the channel walls. The reaction mixture of the hydrogenation reaction can flow through these channels in the flow direction through the reactor. Thus, a much stronger contacting of the reaction mixture with the catalytically active sites usually takes place than with catalyst beds of particulate moldings.

The monolithic shaped bodies used in accordance with the invention are not shaped bodies of single catalyst bodies having a greatest length extension in any direction of less than 1 cm. Such non-monolithic moldings lead to fixed catalyst beds in the form of conventional catalyst beds. The monolithic shaped catalyst bodies used according to the invention have a regular flat or spatial structure, and thereby differ from carriers in particle form, which are used as loose heap.

The monolithic catalyst form bodies used according to the invention have a smallest dimension in a direction of preferably at least 1 cm, particularly preferably at least 2 cm, in particular at least 5 cm, based on the entire molded body. The maximum value for the largest dimension in one direction is in principle not critical and usually results from the production process of the moldings. So z. For example, shaped bodies in the form of foams can be plate-shaped assemblies having a thickness in the range of millimeters to centimeters, a width in the range of a few centimeters to several hundred centimeters and a length (as the largest dimension in one direction) of up to several Meters. In contrast to bulk solids, the monolithic shaped catalyst bodies used according to the invention can preferably be connected in a form-fitting manner to form larger units or consist of units which are larger than bulk materials.

The monolithic shaped catalyst bodies used in accordance with the invention generally also differ from particulate catalysts or their supports in that they are present in substantially fewer parts. Thus, according to the invention, a fixed catalyst bed can be used in the form of a single shaped body. In general, however, several moldings are used to prepare a fixed catalyst bed. The monolithic shaped catalyst bodies used according to the invention generally have extensive three-dimensional structures. The shaped catalyst bodies used according to the invention are generally permeated by continuous channels. The continuous channels may have any geometry, for example, they may be in a honeycomb structure. Suitable shaped catalyst bodies can also be produced by deforming flat carrier structures, for example by rolling up or buckling the two-dimensional ones

Structures to three-dimensional structures. Starting from flat substrates, the outer shape of the molded bodies can be easily adapted to given reactor geometries. The monolithic shaped catalyst bodies used according to the invention are distinguished by the fact that they can be used to produce fixed catalyst beds in which a controlled flow through the fixed catalyst bed is possible. A movement of the catalyst bodies under the conditions of the catalyzed reaction, for. B. a juxtaposition of the shaped catalyst body is avoided. Due to the ordered structure of the catalyst form body and the resulting fixed catalyst bed resulting in improved opportunities for fluidically optimal operation of the fixed catalyst bed. The monolithic shaped catalyst bodies used in the process according to the invention are preferably in the form of a foam, mesh, woven fabric, knitted fabric, knitted fabric or monoliths different therefrom. For the purposes of the invention, the term monolithic catalyst also includes catalyst structures known as "homecomb catalysts".

The catalyst fixed beds used according to the invention have at any section in the normal plane to the flow direction (ie, horizontal) through the fixed catalyst bed, based on the total area of the section, preferably at most 5%, more preferably at most 1%, in particular at most 0.1% free area, the not part of the catalyst bodies. The area of the pores and channels which open at the surface of the shaped catalyst body is not calculated to this free area. The indication of the free area refers exclusively to sections through the fixed catalyst bed in the region of the shaped catalyst body and not possible internals, such as power distribution.

In the context of the invention, pores are understood as meaning voids in the shaped catalyst bodies which have only one opening on the surface of the shaped catalyst bodies. In the context of the invention, channels are understood as meaning cavities in the shaped catalyst bodies which have at least two openings on the surface of the shaped catalyst bodies.

If the fixed catalyst beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, particularly preferably at least 98% of the pores and channels, preferably have an arbitrary section in the normal plane to the flow direction through the catalyst bed. an area of at most 3 mm ² .

If the catalyst fixed beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, more preferably at least 98% of the pores and channels, have an area at any section in the normal plane to the flow direction through the fixed catalyst bed of at most 1 mm ² . If the catalyst fixed beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, more preferably at least 98% of the pores and channels, have an area at any section in the normal plane to the flow direction through the fixed catalyst bed of at most 0.7 mm ² .

In the case of the fixed catalyst beds according to the invention, at least 95% of the reactor cross section, more preferably at least 98% of the reactor cross section, in particular at least 99% of the reactor cross section, is preferably filled with shaped catalyst bodies over at least 90% length in the reactor longitudinal axis.

In a specific embodiment, the shaped catalyst bodies are in the form of a foam. The shaped catalyst bodies may have any suitable outer shapes, for example cubic, cuboid, cylindrical, etc. Suitable fabrics may be produced with different weaves, such as smooth fabrics, body fabrics, woven fabrics, five-shaft atlas fabrics or other special weave fabrics. Also suitable are wire mesh made of weavable metal wires, such as iron, spring steel, brass, phosphor bronze, pure nickel, monel, aluminum, silver, nickel silver (copper-nickel-zinc alloy), nickel, chrome nickel, chromium steel, stainless, acid-resistant and highly heat-resistant chrome-nickel steels Titanium. The same applies to knitted and knitted fabrics. Also, woven, knitted or knitted fabrics of inorganic materials such as AI2O3 and / or S1O2 may be used. Also suitable are woven, knitted or knitted fabrics made of plastics, such as polyamides, polyesters, polyolefins (such as polyethylene, polypropylene), polytetrafluoroethylene, etc. The abovementioned woven, knitted or knitted fabrics, but also other flat-structured catalyst supports can lead to larger spatial structures, so-called monoliths are deformed. It is also possible not to build monoliths from laminar supports, but to produce them directly without intermediate stages, for example the ceramic monoliths with flow channels known to those skilled in the art.

Suitable catalyst bodies are those which are described, for example, in EP-A 0 068 862, EP-A-0 198 435, EP-A 201 614, EP-A 448 884, EP 0 754 664 A2, DE 433 32 93, EP 2 764 916 A1 and US 2008/0171218 A1 are described.

Thus, EP 0 068 862 describes a monolithic molded body comprising alternating layers of smooth and corrugated sheets in the form of a roll having channels and wherein the smooth sheets contain woven, knitted or knitted textile materials and the corrugated sheets contain a mesh material. The EP-A-0 198 435 describes a process for the preparation of catalysts in which the active components and the promoters are applied to support materials by vapor deposition in ultra-high vacuum. The carrier materials used are reticulated or web-like carrier materials. The vapor-deposited catalyst webs are assembled into "catalyst packages" for incorporation into the reactor, and the shape of the catalyst packages is adapted to the flow conditions in the reactor.

Suitable methods for vapor deposition and sputtering of metals in vacuum are known.

Preferably, the shaped catalyst bodies contain at least one element selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd. In a specific embodiment, the shaped catalyst bodies contain Ni. In a specific embodiment, the shaped catalyst bodies contain no palladium. This is understood to mean that no palladium is actively added to produce the shaped catalyst bodies, neither as a catalytically active metal nor as a promoter element, nor to provide the shaped bodies which serve as a carrier material. The catalyst form bodies are preferably a Raney metal catalyst.

The monolithic shaped catalyst bodies are particularly preferably in the form of a foam. In principle, metal foams having different morphological properties with respect to pore size and shape, layer thickness, areal density, geometric surface, porosity, etc. are suitable. The preparation can be carried out in a manner known per se. For example, a foam of an organic polymer may be coated with at least a first metal and then the polymer removed, e.g. Example by pyrolysis or dissolution in a suitable solvent, wherein a metal foam is obtained. For coating with at least a first metal or precursor thereof, the organic polymer foam may be contacted with a solution or suspension containing the first metal. This can be z. B. done by spraying or dipping. Also possible is a deposition by means of chemical vapor deposition (CVD). So z. B. a polyurethane foam coated with the first metal and then the polyurethane foam are pyrolyzed. A suitable for the production of shaped catalyst bodies in the form of a foam polymer foam preferably has a pore size in the range of 100 to 5000 μηη, more preferably from 450 to 4000 μηη and in particular from 450 to 3000 μηη. A suitable polymer foam preferably has a layer thickness of 5 to 60 mm, more preferably from 10 to 30 mm. A suitable polymer foam preferably has a density of from 300 to 1200 kg / m ³ . The specific surface area is preferably in a range of 100 to 20000 m ² / m ³ , particularly preferably 1000 to 6000 m ² / m ³ . The porosity is preferably in a range of 0.50 to 0.95.

The order of the second component can be done in many ways, for. Example by bringing the molded article obtained from the first component with the second component by rolling or dipping in contact or applying the second component by spraying, sprinkling or pouring. For this purpose, the second material may be liquid or preferably in the form of a powder. Also possible is the application of salts of the second component and subsequent reduction. It is also possible to apply the second component in combination with an organic binder. The production of an alloy on the surface of the molding is carried out by heating to the alloying temperature. The alloying conditions make it possible to control the leaching properties of the alloy, as explained above. When Al is used as the second component, the alloying temperature is preferably in a range of 650 to 1,000 ° C, more preferably 660 to 950 ° C. When a NiAl powder is used as the second component, the alloying temperature is preferably in a range of 850 to 900 ° C, more preferably 880 to 900 ° C. It may be advantageous to continuously raise the temperature during the alloy and then keep it at the maximum for a time. Subsequently, the foam-shaped coated and heated shaped catalyst body is allowed to cool.

In a preferred embodiment, to provide the monolithic shaped catalyst bodies: a1) a metal foam molding is provided which comprises at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, a2) applied to the surface of the metal foam molding at least a second component containing an element selected from Al, Zn and Si, and a3) by alloying the metal foam molding obtained in step a2) at least on a part of the surface of an alloy educated.

Such shaped catalyst bodies and processes for their preparation are described in EP 2 764 916 A1, to which reference is made in its entirety. Suitable alloying conditions result from the phase diagram of the metals involved, z. B. the phase diagram of Ni and Al. So z. B. the proportion of Al-rich and leachable components, such as N1AI3 and N12AI3, are controlled. The shaped catalyst bodies may contain dopants in addition to the first and second components. These include z. Mn, V, Ta, Ti, W, Mo, Re, Ge, Sn, Sb or Bi.

Preference is given to shaped catalyst bodies in which the first metal contains Ni or consists of Ni. Preference is furthermore given to shaped catalyst bodies in which the second component contains Al or consists of Al. A particular embodiment is catalyst form bodies containing nickel and aluminum.

For the production of a monolithic shaped catalyst body in the form of a foam, preference is given to using an aluminum powder having a particle size of at least 5 μm. The aluminum powder preferably has a particle size of at most 75 μm.

For the production of a monolithic shaped catalyst body in the form of a foam a1), it is preferred to provide a metal foam body containing Ni, a2) applying to the surface of the metal foam body an aluminum-containing suspension in a solvent, a3) by alloying in step a2) obtained metal foam molding formed at least on a part of the surface of an alloy.

Particularly preferably, the aluminum-containing suspension additionally contains polyvinylpyrrolidone. The amount of the polyvinylpyrrolidone is preferably 0.1 to 5% by weight, more preferably 0.5 to 3% by weight, based on the total weight of the aluminum-containing suspension. The molecular weight of the polyvinylpyrrolidone is preferably in a range of 10,000 to 1,300,000 g / mol.

Particularly preferably, the aluminum-containing suspension contains a solvent which is selected from water, ethylene glycol and mixtures thereof.

The alloying is preferably carried out by stepwise heating in the presence of a gas mixture containing hydrogen and at least one inert gas under the reaction conditions. Nitrogen is preferably used as the inert gas. Suitable is z. Example, a gas mixture containing 50 vol .-% N 2 and 50 vol .-% H. The alloy formation can z. B. done in a rotary kiln. Suitable heating rates are in a range of 1 to 10 K / min, preferably 3 to 6 K / min. It may be advantageous to maintain the temperature substantially constant (isothermal) once or several times during the high heating for a certain time. So z. B. during heating, the temperature at about 300 ° C, about 600 ° C and / or about 700 ° C are kept constant. The time during which the temperature is kept constant is preferably about 1 to 120 minutes, more preferably 5 to 60 minutes. Preferably, the temperature is kept constant in a range of 650 to 920 ° C during the heating. When the temperature is kept constant several times, the last stage is preferably in a range of 650 to 920 ° C. The alloy formation is furthermore preferably carried out with gradual cooling. Cooling is preferably carried out to a temperature in the range from 150 to 250 ° C. in the presence of a gas mixture which contains hydrogen and at least one gas which is inert under the reaction conditions. Nitrogen is preferably used as the inert gas. Suitable is z. Example, a gas mixture containing 50 vol .-% N2 and 50 vol .-% H2. Preferably, the further cooling takes place in the presence of at least one inert gas, preferably in the presence of nitrogen. Preferably, the weight of the monolithic shaped catalyst body in the form of a foam is 35 to 60%, particularly preferably 40 to 50% higher than the weight of the metal foam molding used for its production.

Preferably, the intermetallic phases thus obtained on the support metal skeleton consist mainly of N12Al3 and NlAl3.

Activation (also referred to as step b))

Preferably, the catalyst moldings used for activation, based on the total weight of 60 to 95 wt .-%, particularly preferably 70 to 80 wt .-%, of a first metal which is selected from Ni, Fe, Co, Cu, Cr, Pt , Ag, Au and Pd.

Preferably, the Katalysatorformkorper used for activation, based on the total weight 5 to 40 wt .-%, particularly preferably 20 to 30 wt .-%, of a second component which is selected from Al, Zn and Si.

Preferably, the Katalysatorformkorper used for activation, based on the total weight of 60 to 95 wt .-%, particularly preferably 70 to 80 wt .-%, Ni. Preferably, the catalyst moldings used for activation, based on the total weight of 5 to 40 wt .-%, particularly preferably 20 to 30 wt .-%, AI on.

During activation, the fixed catalyst bed is subjected to a treatment with a maximum of 3.5% by weight aqueous base as the treatment medium, the second (leachable) component of the catalyst moldings being at least partially dissolved and removed from the shaped catalyst bodies. As previously stated, the aqueous base treatment is exothermic so that the fixed catalyst bed heats up as a result of activation. The heating of the fixed catalyst bed is dependent on the concentration of the aqueous base used. If no heat is removed from the reactor by active cooling, but transferred to the treatment medium, so that in a sense an adiabatic procedure is realized, then formed during activation of a temperature gradient in the fixed catalyst bed, the temperature increases in the current direction of the aqueous base. However, even if heat is removed from the reactor by active cooling, a temperature gradient is formed in the fixed catalyst bed during activation.

Preferably 30 to 70 wt .-%, particularly preferably 40 to 60 wt .-%, of the second component, based on the original weight of the second component removed from the shaped catalyst bodies by the activation.

Preferably, the catalyst moldings used for activation contain Ni and Al and, by activation, becomes 30 to 70% by weight, particularly preferably 40 to

60 wt .-%, of AI, based on the original weight removed.

The determination of the dissolved out of the catalyst moldings amount of the second component, for. As aluminum, for example, can be done by elemental analysis by determining the content of the second component in the total amount of discharged laden aqueous base and the washing medium. Alternatively, the determination of the amount of the second component dissolved out of the shaped catalyst bodies can be determined by the amount of hydrogen formed during the course of the activation. In the case in which aluminum is used, in each case 3 mol of hydrogen are produced by dissolving 2 mol of aluminum.

The activation of a catalyst by the process according to the invention can be carried out in bottom or trickle mode. Preference is given to the upflow method, wherein the fresh aqueous base is fed to the marsh side of the fixed catalyst bed and is discharged at the top end after passing through the fixed catalyst bed. After passing through the fixed catalyst bed, a loaded aqueous base is obtained. The loaded aqueous base has a lower base concentration than the aqueous base before passing through the fixed catalyst bed and is enriched in the reaction products formed during activation and at least partially soluble in the base. These reaction products include, for. Example, when using aluminum as the second (leachable) component alkali aluminates, aluminum hydroxide hydrates, hydrogen, etc. (see, for example, US 2,950,260). The statement that the fixed catalyst bed has a temperature gradient during activation is understood in the context of the invention to mean that over a longer period of the total activation the fixed catalyst bed has this temperature gradient. The fixed catalyst bed preferably has a temperature gradient until at least 50% by weight, preferably at least 70% by weight, in particular at least 90% by weight, of the amount of aluminum to be removed has been removed from the shaped catalyst bodies. Unless during the activation the strength of the aqueous base used is increased and / or the temperature of the fixed catalyst bed is increased by less cooling than at the beginning of activation or external heating, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed in the course of activation are increasingly lower and can then take the value of zero towards the end of the activation.

Preferably, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed is kept at a maximum of 50 K. To determine the temperature difference in the course of the fixed catalyst bed, this can be provided with conventional measuring devices for temperature measurement. For determining the temperature difference between the warmest point of the fixed catalyst bed and the coldest point of the fixed catalyst bed, it is generally sufficient for a non-actively cooled reactor to determine the temperature difference between the most upstream location of the fixed catalyst bed and the most downstream location of the fixed catalyst bed , In an actively cooled reactor, it may be useful to provide at least one additional temperature sensor in the flow direction between the most upstream location of the fixed catalyst bed and the most downstream location of the fixed catalyst bed (eg, 1, 2, or 3 more temperature sensors). Particularly preferably, the temperature difference between the coldest point of the catalyst fixed bed and the warmest point of the fixed catalyst bed is maintained at a maximum of 40 K, in particular at a maximum of 25 K. Preferably, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed at the beginning of activation in a range of 0.1 to 50 K, preferably in a range of 0.5 to 40 K, in particular in a range of 1 to 25K, kept. It is possible initially to initially introduce an aqueous medium without base and then to add fresh base until the desired concentration has been reached. In this case, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed at the beginning of the activation means the time at which the desired base concentration at the inlet to the reactor is reached for the first time.

The control of the size of the temperature gradient in the fixed catalyst bed can be carried out in a non-actively cooled reactor by selecting the amount and concentration of the supplied aqueous base according to the heat capacity of the medium used for activation. To control the size of the temperature gradient in the fixed catalyst bed in an actively cooled reactor, heat is also removed from the medium used for activation by heat exchange. Such removal of heat can be done by cooling the medium used for activation in the reactor used and / or, if present, the liquid circulation stream.

The shaped catalyst bodies are preferably subjected to the activation of a treatment with a maximum of 3.5% by weight aqueous base. Particularly preferred is the use of a maximum of 3.0 wt .-% aqueous base. The shaped catalyst bodies are preferably subjected to the activation of a treatment with a 0.1 to 3.5% by weight aqueous base, particularly preferably a 0.5 to 3.5% strength by weight aqueous base. The concentration is based on the maximum of 3.5% by weight aqueous base prior to their contact with the catalyst bodies. If, for activation, the aqueous base is brought into contact only once with the shaped catalyst bodies, the concentration information relates to the fresh aqueous base. If, for activation, the aqueous base is passed at least partly in a liquid circulation stream, then the laden base obtained after the activation can be added before it is used again to activate the shaped catalyst bodies fresh base. The previously indicated concentration values apply analogously. By maintaining the above-mentioned concentrations for the aqueous base catalyst shaped bodies of Raney metal catalysts are obtained with high activity and very good stability. This is especially true for the activation of fixed catalyst beds for hydrogenation reactions on an industrial scale. Surprisingly, an excessively high temperature increase and the uncontrolled formation of hydrogen in the activation of the catalysts are effectively avoided with the given concentration ranges of the base. This advantage has a special effect on reactors on an industrial scale. In a preferred embodiment, the maximum of 3.5% by weight aqueous base used for activation is conducted at least partially in a liquid circulation stream. In a first embodiment, the reactor is operated with the catalyst to be activated in the upflow mode. Then, in a vertically oriented reactor, the aqueous base is fed to the sump side of the reactor, passed from bottom to top through the fixed catalyst bed, taken above the fixed catalyst bed a discharge and returned to the sump side in the reactor. The discharged stream is preferably a workup, z. B. by separation of hydrogen and / or the discharge of a portion of the loaded aqueous base. In a second embodiment, the reactor is operated in trickle mode with the catalyst to be activated. Then, in a vertically oriented reactor, the aqueous base is fed into the top of the reactor, passed from top to bottom through the fixed catalyst bed, removed below the fixed catalyst bed and discharged back into the reactor at the top. In this case, the discharged current is preferably in turn a workup, z. B. by separation of hydrogen and / or the discharge of a portion of the loaded aqueous base. Preferably, the activation takes place in a vertical reactor in the upflow mode (ie with an upward flow through the fixed catalyst bed). Such a procedure is advantageous if the formation of hydrogen during activation also produces a low gas load, since this can be more easily removed overhead.

In a preferred embodiment, fresh aqueous base is added to the fixed catalyst bed in addition to the base carried in the liquid recycle stream. The supply of fresh base can be done in the liquid recycle stream or separately in the reactor. In this case, the fresh aqueous base may also be concentrated higher than 3.5 wt .-%, provided that after mixing with the recycled aqueous base, the base concentration is not higher than 3.5 wt .-%. The ratio of aqueous base passed in the circulation stream to freshly supplied aqueous base is preferably in a range from 1: 1 to 1000: 1, more preferably from 2: 1 to 500: 1, in particular from 5: 1 to 200: 1.

Preferably, the feed rate of the aqueous base (when the aqueous base used for activation is not conducted in a liquid recycle stream) is at most 5 L / min per liter fixed catalyst bed, preferably at most 1.5 L / min per liter fixed catalyst bed, more preferably at most 1 L / min per liter of fixed catalyst bed, based on the total volume of the fixed catalyst bed.

The aqueous base used for activation is preferably conducted at least partly in a liquid circulation stream and the feed rate of the freshly fed aqueous base is at most 5 L / min per liter of fixed catalyst bed, preferably at most 1.5 L / min per liter of fixed catalyst bed, more preferably at most 1 L / min per liter of fixed catalyst bed, based on the total volume of the fixed catalyst bed.

Preferably, the feed rate of the aqueous base (when the aqueous base used for activation is not carried in a liquid recycle stream) is in the range of 0.05 to 5 L / min per liter of fixed catalyst bed, more preferably in the range of 0.1 to 1 , 5 L / min per liter of fixed catalyst bed, in particular in a range of 0.1 to 1 L / min per liter of fixed catalyst bed, based on the total volume of Kata lysatorf estbetts. Preferably, the aqueous base used for the activation is at least partially conducted in a liquid circulation stream and the feed rate of the freshly supplied aqueous base is in a range of 0.05 to 5 L / min per liter of fixed catalyst bed, more preferably in a range of 0.1 to 1.5 L / min per liter of fixed catalyst bed, in particular in a range of 0.1 to 1 L / min per liter of fixed catalyst bed, based on the total volume of the fixed catalyst bed.

This control of the fresh aqueous base feed rate is an effective way to maintain the temperature gradient resulting in the fixed catalyst bed within the desired range of values.

The flow rate of the aqueous base through the reactor containing the fixed catalyst bed is preferably at least 0.5 m / h, more preferably at least 3 m / h, especially at least 5 m / h, especially at least 10 m / h. In order to avoid mechanical stress and abrasion of the newly formed porous catalyst metal, it may be useful not to choose the flow rate too high. The flow rate of the aqueous base through the reactor containing the fixed catalyst bed is preferably at most 100 m / h, more preferably at most 50 m / h, especially at most 40 m / h.

The above-mentioned flow rates can be achieved particularly well if at least some of the aqueous base is conducted in a liquid circulation stream.

The base used to activate the fixed catalyst bed is selected from alkali metal hydroxides, alkaline earth metal hydroxides and mixtures thereof. Preferably, the base is selected from NaOH, KOH and mixtures thereof. Specifically, NaOH is used as the base. The base is used for activation in the form of an aqueous solution.

The method according to the invention makes it possible to effectively minimize a detachment of the catalytically active metal, such as nickel, during the activation. A suitable measure of the effectiveness of the activation and the stability of the obtained Raney metal catalyst is the metal content in the loaded aqueous base. When using a liquid circulation stream, the metal content in the circulation stream is a suitable measure of the effectiveness of the activation and the stability of the resulting Raney metal catalyst. The content of nickel during activation in the loaded aqueous base or, if a liquid circulation stream is used for activation, in the circulation stream is preferably at most 0.1% by weight, more preferably at most 100 ppm by weight, especially at most 10% by weight .-ppm. The determination of the nickel content can be done by elemental analysis. The same advantageous values are generally also achieved in the following process steps, such as treatment of the activated catalyst fixed bed with a washing medium, treatment of the catalyst fixed bed with a dopant and use in a hydrogenation reaction.

The inventive method allows a homogeneous distribution of the catalytically active Raney metal on the moldings used and a total of the resulting activated fixed catalyst bed. No or only a slight gradient with respect to the distribution of the catalytically active Raney metal in the direction of flow of the activation medium through the fixed catalyst bed is formed. In other words, the concentration of catalytically active sites upstream of the fixed catalyst bed is substantially equal to the concentration of catalytically active sites downstream of the fixed catalyst bed. This advantageous effect is achieved in particular when the Activation used aqueous base is at least partially conducted in a liquid circulation stream. The inventive method also allow a homogeneous distribution of the leached second component, eg. As the aluminum, on the moldings used and a total of the resulting activated catalyst fixed bed. There is no or only a slight gradient with respect to the distribution of the leached second component in the flow direction of the activation medium through the fixed catalyst bed.

Another advantage, if the aqueous base used for activation is at least partially conducted in a liquid circulation stream, is that the required amount of aqueous base can be significantly reduced. Thus, a straight pass of the aqueous base (without recycling) and the subsequent discharge of the loaded base leads to a high demand for fresh base. By supplying suitable amounts of fresh base into the recycle stream, it is ensured that there is always sufficient base for the activation reaction. All in all, significantly lower quantities are required for this.

As stated above, after passing through the fixed catalyst bed, a charged aqueous base is obtained which has a lower base concentration than the aqueous base before passing through the fixed catalyst bed, and the reaction products formed during activation and at least partially soluble in the base enriched. Preferably, at least part of the loaded aqueous base is discharged. Thus, even if a portion of the aqueous base is passed in a recycle stream, excessive dilution and accumulation of undesirable impurities in the aqueous base used for activation can be avoided. The amount of aqueous base freshly supplied per unit time preferably corresponds to the amount of laden aqueous base removed.

Preferably, a discharge of laden aqueous base is removed from the activation and subjected to a gas / liquid separation, a hydrogen-containing gas phase and a liquid phase being obtained. For gas / liquid separation, it is possible to use the customary devices known to the person skilled in the art, such as the customary separation containers. The hydrogen-containing gas phase obtained in the phase separation can be discharged from the process and z. B. be supplied to a thermal utilization. The liquid phase obtained in the phase separation, which contains the discharged laden aqueous base is preferably at least partially recycled as a liquid recycle stream in the activation. Preferably, part of the liquid phase obtained in the phase separation, which contains the discharged laden aqueous base, is discharged. Thus, as described above, a Too much dilution and an accumulation of unwanted impurities in the aqueous base used for activation can be avoided.

To control the progress of the activation and to determine the amount of the second component dissolved out of the catalyst tablets, eg. As aluminum, the amount of hydrogen formed during the activation can be determined. In the case in which aluminum is used, in each case 3 mol of hydrogen are produced by dissolving 2 mol of aluminum. The activation according to the invention preferably takes place at a temperature of at most 50 ° C., preferably at a temperature of at most 40 ° C.

The activation according to the invention preferably takes place at a pressure in the range from 0.1 to 10 bar, more preferably from 0.5 to 5 bar, especially at ambient pressure.

Treatment with a washing medium (also referred to as optional step c))

In optional step c) of the process according to the invention, the activated catalyst fixed bed obtained in step b) is subjected to a treatment with a washing medium which is selected from water, C 1 -C 4 alkanols and mixtures thereof.

Suitable C 1 -C 4 -alkanols are methanol, ethanol, n-propanol, isopropanol, n-butanol and isobutanol. Preferably, the washing medium used in step c) contains water or consists of water.

The treatment with the washing medium is preferably carried out in step c) until the effluent washing medium has a conductivity at 20 ° C. of at most 200 mS / cm, particularly preferably at most 100 mS / cm, in particular at most

10 mS / cm.

In step c), water is preferably used as the washing medium and the treatment with the washing medium is carried out until the effluent washing medium has a pH at 20 ° C. of not more than 9, particularly preferably not more than 8, in particular not more than 7.

The treatment with the washing medium is preferably carried out in step c) until the effluent washing medium has an aluminum content of at most 5% by weight, more preferably of at most 5000 ppm by weight, in particular of at most 500 ppm by weight.

In step c), the treatment with the washing medium is preferably carried out at a temperature in the range from 20 to 100.degree. C., particularly preferably from 30 to 80.degree. C., in particular from 40 to 70.degree.

Doping (also referred to as step d)) Doping refers to the introduction of foreign atoms in a layer or in the base material of a catalyst. The amount introduced in this process is generally small compared to the rest of the catalyst material. The doping specifically changes the properties of the starting material. According to the invention, the fixed catalyst bed after activation (ie following step b)) and optionally after treatment with a washing medium (ie also following step c), if this is carried out with a Dopant brought into contact, which has at least one element which is different from the first metal and the second component of the catalyst used in step a) molded article. Such elements are referred to hereinafter as "promoter elements". Preferably, contacting with the dopant occurs during and / or after treatment of the activated fixed catalyst bed with a wash medium (i.e., during and / or after step c)). The dopant preferably contains at least one promoter element selected from Ti, Ta, Zr, V, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Ce and Bi.

It is possible that the dopant contains at least one promoter element which simultaneously fulfills the definition of a first metal in the sense of the invention. Such promoter elements are selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd. In this case, the monolithic molded article contains, based on the reduced metallic form, a major amount (ie, more than 50% by weight) of the first metal and a minor amount (ie, less than 50% by weight) of a different metal as a dopant , When specifying the total amount of the first metal that contains the monolithic shaped catalyst body, however, all metals that meet the definition of a first metal according to the invention are calculated with their full weight fraction (regardless of whether they act as a hydrogenation-active component or as a promoter). In a specific embodiment, the dopant does not contain a promoter element which fulfills the definition of a first metal in the sense of the invention. The dopant then preferably contains exclusively one promoter element or more than one promoter element which is selected from Ti, Ta, Zr, Ce, V, Mo, W, Mn, Re, Ru, Rh, Ir and Bi.

Preferably, the dopant contains Mo as a promoter element. In a specific embodiment, the dopant contains Mo as the sole promoter element. The promoter elements are particularly preferably used for doping in the form of their salts. Suitable salts are, for example, the nitrates, sulfates, acetates, formates, fluorides, chlorides, bromides, iodides, oxides or carbonates. The promoter elements either separate by themselves in their metallic form due to their nobler character compared to Ni or can be brought into contact with a reducing agent such as e.g. As hydrogen, hydrazine, hydroxylamine, etc., are reduced in their metallic form. If the promoter elements are added during the activation process, then they can also be in their metallic form. In this case, it may be useful for the formation of metal-metal compounds to subject the fixed catalyst bed after the storage of the promoter metals first an oxidative treatment and then a reducing treatment.

In a specific embodiment, the fixed catalyst bed is contacted during and / or after treatment with a wash medium in step c) with a dopant containing Mo as a promoter element. More specifically, the dopant contains Mo as the sole promoter element. Suitable molybdenum compounds are selected from molybdenum trioxide, the nitrates, sulfates, carbonates, chlorides, iodides and bromides of molybdenum and the molybdates. Preference is given to the use of ammonium molybdate. In a preferred embodiment, a molybdenum compound is used which has good water solubility. A good water solubility is understood to mean a solubility of at least 20 g / L at 20 ° C. When using molybdenum compounds, which have a lower water solubility, it may be useful before they are used as a dopant to filter the solution. Suitable solvents for doping are water, polar solvents which are different from water and solvents which are inert to the catalyst under the doping conditions, and mixtures thereof. Preferably, the solvent used for doping is selected from water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and mixtures thereof. The temperature during the doping is preferably in a range from 10 to 100 ° C., more preferably from 20 to 60 ° C., in particular from 20 to 40 ° C.

The concentration of the promoter element in the dopant is preferably in a range of about 20 g / L to the maximum soluble amount of the dopant under the doping conditions. As a rule, one will assume a maximum of one solution saturated at ambient temperature.

The duration of the doping is preferably 0.5 to 24 hours.

It may be advantageous for the doping to take place in the presence of an inert gas. Suitable inert gases are for. As nitrogen or argon.

In a specific embodiment for doping foam-like shaped catalyst bodies, a molybdenum source is dissolved in water and this solution is passed through the previously activated foam. When using hydrates of ammonium molybdate, such as. B. (ΝΗ4) 6Μθ7θ24 x 4 H2O, this is dissolved in water and this solution used. The usable amount depends strongly on the solubility of the ammonium molybdate and is in principle not critical. Conveniently, less than 430 grams of ammonium molybdate are dissolved per liter of water at room temperature (20 ° C). If the doping is carried out at a higher temperature than room temperature, then larger amounts can be used. The ammonium molybdate solution is then passed over the activated and washed foam at a temperature of 20 to 100 ° C, preferably at a temperature of 20 to 40 ° C. The treatment time is preferably 0.5 to 24 hours, more preferably 1 to 5 hours. In a specific embodiment, the contacting takes place in the presence of an inert gas, such as nitrogen. The pressure is preferably in a range of 1 to 50 bar, especially at about 1 bar absolute. Thereafter, the doped Raney nickel foam can be used either without further work-up or after repeated washing for the hydrogenation.

The doped catalyst bodies preferably contain from 0.01 to 10% by weight, particularly preferably from 0.1 to 5% by weight, of promoter elements based on the reduced metallic form of the promoter elements and the total weight of the catalyst moldings.

The fixed catalyst bed may contain the promoter elements substantially homogeneously or heterogeneously distributed in their concentration. In a specific embodiment, the fixed catalyst bed has a gradient in the flow direction the concentration of the promoter elements. In particular, the fixed catalyst bed contains Ni / Al catalyst bodies doped with Mo, or the fixed catalyst bed is Ni / Al catalyst bodies doped with Mo, and the fixed catalyst bed has a gradient in Mo flow direction.

It is possible to obtain a fixed bed catalyst which is fixedly installed in a reactor and which contains at least one promoter element which substantially homogeneously distributes in its concentration, i. H. not in the form of a gradient. To provide such a fixed bed catalyst, it is possible not to dope the catalyst in built-in form in the fixed bed reactor itself, possibly with circulation, whereby a concentration gradient can arise. Preferably, the doping is then carried out in an external container without circulation, which is infinitely back-mixed, such. B. a batch reactor without continuous feed and drain. After completion of doping and, if appropriate, a washing, such catalysts can be incorporated in a fixed bed reactor with or without a circulation and are thus without gradients.

To provide a fixed catalyst bed having a gradient in the flow direction with respect to the concentration of promoter elements, one can proceed by passing a liquid stream of the dopant through the fixed catalyst bed. If the reactor has a circulation stream, it is alternatively or additionally possible to feed the dopant in liquid form into the circulation stream. In such an approach, a concentration gradient of the promoter elements is formed over the entire length of the fixed catalyst bed in the flow direction. If it is desired that the concentration of the promoter element in the flow direction of the reaction medium of the reaction to be catalyzed decreases, the liquid flow of the dopant is conducted in the same direction as the reaction medium of the reaction to be catalyzed by the fixed catalyst bed. If it is desired that the concentration of the promoter element increases in the direction of flow of the reaction medium of the reaction to be catalyzed, the liquid flow of the dopant is directed in the opposite direction as the reaction medium of the reaction to be catalyzed by the fixed catalyst bed.

In a first preferred embodiment, the activated catalyst fixed bed obtained by the process according to the invention or a reactor containing such an activated fixed catalyst bed for the hydrogenation of 1, 4-butynediol to give 1, 4-butanediol. It has now surprisingly been found that a particularly high selectivity is achieved in the hydrogenation, if a fixed catalyst bed Ni / Al catalyst moldings are used, which are activated by the method according to the invention and / or which are doped with Mo and wherein the concentration of molybdenum in the flow direction of the reaction medium of the hydrogenation reaction increases. The molybdenum content of the shaped catalyst bodies at the entry of the reaction medium into the fixed catalyst bed is preferably 0 to 3% by weight, more preferably 0.05 to 2.5% by weight, in particular 0.1 to 2% by weight, based on metallic molybdenum and the total weight of the catalyst form body. The molybdenum content of the shaped catalyst bodies at the outlet of the reaction medium from the fixed catalyst bed is preferably from 0.1 to 10% by weight, more preferably from 0.1 to 7% by weight, in particular from 0.2 to 6% by weight, based on metallic molybdenum and the total weight of the shaped catalyst bodies.

In a second preferred embodiment, the activated catalyst fixed bed obtained by the process of the present invention or a reactor containing such an activated fixed catalyst bed is used for the hydrogenation of 4-butyraldehyde to give n-butanol. It has now surprisingly been found that a particularly high selectivity is achieved in the hydrogenation, if one uses a fixed catalyst bed of Ni / Al catalyst moldings, which are activated by the novel process and / or which are doped with Mo and wherein the concentration of Molybdenum decreases in the flow direction of the reaction medium of the hydrogenation reaction. Preferably, the molybdenum content of the catalyst molding is at the entry of the reaction medium in the fixed catalyst bed 0.5 to 10 wt .-%, particularly preferably 1 to 9 wt .-%, in particular 1 to 7 wt .-%, based on metallic molybdenum and the total weight of catalyst bodies. Preferably, the molybdenum content of the shaped catalyst bodies at the outlet of the reaction medium from the fixed catalyst bed 0 to 7 wt .-%, particularly preferably 0.05 to 5 wt .-%, in particular 0.1 to 4.5 wt .-%, based on metallic molybdenum and the total weight of the shaped catalyst bodies. It has been found that it is advantageous for the efficiency of the doping of Raney metal catalysts and especially Raney nickel catalysts with a promoter element, especially Mo, if after activation and before doping the activated fixed catalyst bed of a treatment is subjected to a washing medium. This applies in particular if foam-like Raney nickel catalysts are used for the doping. It has been found, in particular, that the adsorption of molybdenum on the shaped catalyst bodies is incomplete if, after activation, the content of washable aluminum is still too high. Preferably, therefore, before the doping in step d), the treatment with a washing medium in step c) is carried out until the effluent washing medium at a temperature of 20 ° C, a conductivity of not more than 200 mS / cm. The treatment with the washing medium is preferably carried out in step c) until the effluent washing medium has an aluminum content of at most 500 ppm by weight. The activated catalyst fixed beds obtained by the process according to the invention, which optionally contain doped shaped catalyst bodies, are generally distinguished by high mechanical stability and long service life. Nevertheless, the fixed bed catalyst is mechanically stressed when it is flowed through in the liquid phase with the components to be hydrogenated. In the long term, wear or removal of the outer layers of the active catalyst species may occur. If the Raney nickel foam catalyst was prepared by leaching and doping, then the subsequently doped metal element is preferably on the outer active catalyst layers, which can also be removed by mechanical liquid or gas loading. Removal of the promoter element may result in reduced activity and selectivity of the catalyst. Surprisingly, it has now been found that the original activity can be restored by the doping process is carried out again. Alternatively, the dopant can also be added to the hydrogenation, which is then post-doped in situ (Method 4).

hydrogenation

In the context of the invention, hydrogenation is understood in general to mean the reaction of an organic compound with H 2 addition to this compound. Preferably, functional groups are hydrogenated to the correspondingly hydrogenated groups. These include, for example, the hydrogenation of nitro groups, nitroso groups, nitrile groups or imine groups to amine groups. This includes, for example, the hydrogenation of aromatics to saturated cyclic compounds. This also includes, for example, the hydrogenation of carbon-carbon triple bonds to form double bonds and / or single bonds. This includes, for example, the hydrogenation of carbon-carbon double bonds to single bonds. This includes, for example, the hydrogenation of ketones, aldehydes, esters, acids or anhydrides to alcohols. Preferably, the hydrogenation of carbon-carbon triple bonds, carbon-carbon double bonds, aromatic compounds, carbonyl-containing compounds, nitriles and nitro compounds. Carbonyl-containing compounds suitable for hydrogenation are ketones, aldehydes, acids, esters and anhydrides. Particularly preferred is the hydrogenation of carbon-carbon triple bonds, carbon-carbon double bonds, nitriles, ketones and aldehydes. The hydrogenatable organic compound is particularly preferably selected from 1,4-butynediol, 1,4-butenediol, 4-hydroxybutyraldehyde, hydroxypivalic acid, hydroxypivalaldehyde, n- and isobutyraldehyde, n- and isovaleraldehyde, 2-ethylhex-2-enal , 2-ethylhexanal, nonanals, 1, 5,9-cyclododecatriene, benzene, furan, furfural, phthalic acid esters, acetophenone and alkyl-substituted acetophenones. The hydrogenatable organic compound is most preferably chosen from 1,4-butynediol, 1,4-butenediol, n- and isobutyraldehyde, hydroxypivalaldehyde, 2-ethylhex-2-enal, nonanals and 4-isobutylacetophenone.

The hydrogenation according to the invention leads to hydrogenated compounds which accordingly no longer contain the group to be hydrogenated. Contains a compound at least two different hydrogenatable groups, it may be desirable to hydrogenate only one of the unsaturated groups, for. For example, when a compound has an aromatic ring and additionally a keto group or an aldehyde group. This includes z. Example, the hydrogenation of 4-isobutylacetophenone to 1 - (4'-isobutylphenyl) - ethanol or the hydrogenation of a C-C-unsaturated ester to the corresponding saturated ester. In principle, at the same time or instead of a hydrogenation in the context of the invention, an undesired hydrogenation of other hydrogenatable groups can be carried out, for. As carbon-carbon single bonds or C-OH bonds to water and hydrocarbons. This includes z. B. the hydrogenolysis of 1, 4-butanediol to propanol or butanol. These latter hydrogenations usually lead to undesirable by-products and are therefore not desirable. Preferably, the hydrogenation according to the invention in the presence of a suitably activated catalyst is characterized by a high selectivity with respect to the desired hydrogenation reactions. These include in particular the hydrogenation of 1, 4-butynediol or 1, 4-butenediol to 1, 4-butanediol. In particular, this includes the hydrogenation of n- and iso-butyraldehyde to n- and iso-butanol. In particular, this includes the hydrogenation of hydroxypivalaldehyde or of hydroxypivalic acid to neopentyl glycol. In particular, this includes the hydrogenation of 2-ethylhex-2-enal to 2-ethylhexanol. In particular, this includes the hydrogenation of nonanals to nonanols. In particular, this includes the hydrogenation of 4-isobutylacetophenone to give 1- (4'-isobutylphenyl) ethanol.

The hydrogenation is preferably carried out continuously. In the simplest case, the hydrogenation takes place in a single hydrogenation reactor. In a specific embodiment of the process according to the invention, the hydrogenation is carried out in n hydrogenation reactors connected in series (in series), n being an integer of at least 2. Suitable values for n are 2, 3, 4, 5, 6, 7, 8, 9 and 10. Preference is given to n for 2 to 6 and in particular for 2 or 3. In this embodiment, the hydrogenation is preferably carried out continuously.

The reactors used for the hydrogenation may have a fixed catalyst bed, which is formed from the same or different shaped catalyst bodies. The fixed catalyst bed may have one or more reaction zones. Various reaction zones may comprise shaped catalyst bodies of different chemical composition of the catalytically active species. Different reaction zones may also have catalyst moldings of the same chemical composition of the catalytically active species but in different concentrations. If at least two reactors are used for the hydrogenation, the reactors may be the same or different reactors. These can be z. B. each have the same or different mixing characteristics and / or be subdivided by internals one or more times. Suitable pressure-resistant reactors for the hydrogenation are known to the person skilled in the art. These include the commonly used reactors for gas-liquid reactions, such as. Pipe reactors, shell and tube reactors, gas recycle reactors, etc. A particular embodiment of the tubular reactors are shaft reactors. The process according to the invention will be carried out in a fixed bed procedure. The fixed bed mode can be z. B. in sump or in trickle run.

The reactors used for the hydrogenation comprise a catalyst fixed bed activated by the processes according to the invention, through which the reaction medium flows. The fixed catalyst bed can be formed from a single variety of shaped catalyst bodies or from different shaped catalyst bodies. The fixed catalyst bed may have one or more zones, wherein at least one of the zones contains a material active as a hydrogenation catalyst. Each zone can have one or more different catalytically active materials and / or one or more different inert materials. Different zones may each have the same or different compositions. It is also possible to provide a plurality of catalytically active zones, which are separated from each other, for example, by inert beds or spacers. The individual zones can also be have different catalytic activity. For this purpose, various catalytically active materials can be used and / or at least one of the zones an inert material can be added. The reaction medium flowing through the fixed catalyst bed contains at least one liquid phase. The reaction medium may also contain a gaseous phase in addition.

In a specific embodiment, the hydrogenation is carried out by the process according to the invention in the presence of CO. During the hydrogenation, the CO content in the gas phase within the reactor is preferably in a range from 0.1 to 10,000 ppm by volume, more preferably in a range from 0.15 to 5000 ppm by volume, in particular in a range from 0, 2 to 1000 ppm by volume. The total CO content within the reactor is composed of CO in the gas and liquid phases, which are in equilibrium with each other. Conveniently, the CO content is determined in the gas phase and the values given here refer to the gas phase.

In this case, a concentration profile over the reactor is advantageous, wherein the concentration of CO in the flow direction of the reaction medium of the hydrogenation along the reactor should increase.

It has now surprisingly been found that a particularly high selectivity is achieved in the hydrogenation, when the concentration of CO in the flow direction of the reaction medium of the hydrogenation reaction increases. The CO content at the outlet of the reaction medium from the fixed catalyst bed is preferably at least 5 mol% higher, more preferably at least 25 mol% higher, in particular at least 75 mol% higher, than the CO content when the reaction medium enters the fixed catalyst bed. To generate a CO gradient in the flow direction of the reaction medium through the fixed catalyst bed, for example, CO can be fed into the fixed catalyst bed at one or more points.

The content of CO is determined, for example, by gas chromatography via removal of individual samples or preferably by online measurement. When samples are taken, it is advantageous, in particular in front of the reactor, to remove both gas and liquid and to relax in order to ensure that a balance between gas and liquid has formed; CO is then determined from the gas phase. The online measurement can be done directly in the reactor, z. B. before the reaction medium enters the fixed catalyst bed and after the exit of the reaction medium from the fixed catalyst bed. The CO content may, for. B. be adjusted by the addition of CO to the hydrogen used for the hydrogenation. Of course, CO can also be fed separately from the hydrogen in the reactor. If the hydrogenation reaction mixture is at least partly conducted in a liquid circulation stream, CO can also be fed into this circulation stream. CO can also be formed from components which are contained in the hydrogenation reaction mixture, eg. B. as starting materials to be hydrogenated or as incurred in the hydrogenation intermediates or by-products. So can CO z. B. be formed by decarbonylation present in the reaction mixture of the hydrogenation formic acid, formates or formaldehyde. Likewise CO can also be formed by decarbonylation of aldehydes other than formaldehyde or by dehydrogenation of primary alcohols to aldehydes and subsequent decarbonylation. These undesirable side reactions include, for. As CC or CX cleavages, such as the formation of propanol or butanol formation of 1, 4-butanediol. It has furthermore been found that the conversion in the hydrogenation can only be insufficient if the CO content in the gas phase within the reactor is too high, ie especially above 10,000 ppm by volume.

The conversion in the hydrogenation is preferably at least 90 mol%, particularly preferably at least 95 mol%, in particular at least 99 mol%, especially at least 99.5 mol%, based on the total weight of hydrogenatable components in the starting material used for the hydrogenation , The conversion refers to the amount of target compound obtained, regardless of how many molar equivalents of hydrogen have taken up the starting compound to reach the target compound. When a starting compound used in the hydrogenation contains a plurality of hydrogenatable groups or contains a hydrogenatable group capable of accepting hydrogen (eg, an alkyne group), the intended target compound may be both the product of partial hydrogenation (eg, alkyne Alkene) or a complete hydrogenation (eg alkyne to alkane).

As already explained above for the activation of the fixed catalyst bed according to the invention, it is important for the success of the hydrogenation according to the invention that the reaction mixture of the hydrogenation (ie gas and liquid stream) predominantly flows through the structured catalyst and does not flow past it, as is the case for example with ordinary, packed fixed-bed catalysts. Preferably, more than 90% of the material stream (ie the sum of gas and liquid stream) should flow through the fixed catalyst bed, preferably over 95%, more preferably> 99%. As stated above, the fixed catalyst beds used according to the invention have, at an arbitrary section in the normal plane to the flow direction (ie, horizontal) through the fixed catalyst bed, preferably at most 5%, particularly preferably at most 1%, in particular at most 0.1%, based on the total area of the section Surface on which is not part of the catalyst bodies. As a free surface, which is part of the shaped catalyst body, the surface of the pores and channels of the shaped catalyst body is understood. This information refers to cuts through the fixed catalyst bed in the region of the shaped catalyst bodies and not any internals, such as power distribution. If the catalyst fixed beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, more preferably at least 98% of the pores and channels, have an area at any section in the normal plane to the flow direction through the fixed catalyst bed of not more than 3 mm ² .

If the catalyst fixed beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, more preferably at least 98% of the pores and channels, have an area at any section in the normal plane to the flow direction through the fixed catalyst bed of at most 1 mm ² .

If the fixed catalyst beds used in accordance with the invention comprise shaped catalyst bodies which have pores and / or channels, then at least 90% of the pores and channels, particularly preferably at least 98% of the pores and channels, preferably have an arbitrary section in the normal plane to the flow direction through the catalyst bed. an area of at most 0.7 mm ² .

In the case of the fixed catalyst beds according to the invention, at least 95% of the reactor cross-section, more preferably at least 98% of the reactor cross-section, in particular at least 99% of the reactor cross-section, is filled with shaped catalyst bodies for at least 90% length in the direction of flow through the fixed catalyst bed. In order for good mass transfer to take place in the structured catalysts, the rate at which the reaction mixture flows through the fixed catalyst bed should not be too low. The flow rate of the reaction mixture through the reactor containing the fixed catalyst bed is preferably at least 30 m / h, preferably at least 50 m / h, in particular at least 80 m / h. The flow rate of the reaction mixture through the reactor containing the fixed catalyst bed is preferably at most 1000 m / h, particularly preferably at most 500 m / h, in particular at most 400 m / h. The flow direction of the reaction mixture is, in principle in an upright reactor, not of critical importance. The hydrogenation can thus be carried out in bottoms or Rieselfahrweise. The upflow mode, wherein the reaction mixture to be hydrogenated is fed to the marsh side of the fixed catalyst bed and is discharged at the top end after passing through the fixed catalyst bed, may be advantageous. This is especially true when the gas load should be low (eg <50 m / h). These flow rates are generally achieved by recycling a portion of the liquid stream leaving the reactor, with the recycle stream combining with the reactant stream either before the reactor or in the reactor. The educt stream can also be supplied distributed over the length and / or width of the reactor.

In a preferred embodiment, the hydrogenation reaction mixture is at least partially conducted in a liquid recycle stream. The ratio of reaction mixture conducted in the circulation stream to freshly fed educt stream is preferably in a range from 1: 1 to 1000: 1, preferably from 2: 1 to 500: 1, in particular from 5: 1 to 200: 1.

A discharge is preferably taken from the reactor and subjected to a gas / liquid separation, a hydrogen-containing gas phase and a product-containing liquid phase being obtained. For gas / liquid separation, it is possible to use the customary devices known to the person skilled in the art, such as the customary separation containers (separators). The temperature in the gas / liquid separation is preferably equal to or lower than the temperature in the reactor. The pressure in the gas / liquid separation is preferably equal to or less than the pressure in the reactor. The gas / liquid separation preferably takes place essentially at the same pressure as in the reactor. The pressure difference between reactor and

Gas / liquid separation is preferably at most 10 bar, in particular at most 5 bar. It is also possible to design the gas / liquid separation in two stages. The absolute pressure in the second gas / liquid T rennung is then preferably in a range of 0.1 to 2 bar.

The product-containing liquid phase obtained in the gas / liquid separation is generally at least partially discharged. From this discharge, the product of the hydrogenation can be isolated, if appropriate after a further work-up. In a preferred embodiment, the product-containing liquid phase is at least partially recycled as a liquid circulation stream in the hydrogenation. The hydrogen-containing gas phase obtained in the phase separation can be at least partially discharged as exhaust gas. Furthermore, the hydrogen-containing gas phase obtained in the phase separation can be at least partially attributed to the hydrogenation. The amount of hydrogen discharged via the gas phase is preferably 0 to 500 mol% of the amount of hydrogen which is consumed in molar amounts of hydrogen in the hydrogenation. For example, with a consumption of one mole of hydrogen, 5 moles of hydrogen can be discharged as exhaust gas. Particularly preferably, the amount of hydrogen discharged via the gas phase is at most 100 mol%, in particular at most 50 mol%, of the amount of hydrogen which is consumed by molar amount of hydrogen in the hydrogenation. By means of this discharge stream can control the CO content in the gas phase in the reactor. In a specific embodiment, the hydrogen-containing gas phase obtained in the phase separation is not recycled. However, if it should be desired, this is preferably up to 1000% of the amount based on the amount of gas required chemically for the reaction, more preferably up to 200%.

The gas loading, expressed by the gas empty tube velocity at the reactor outlet, under reaction conditions is generally below 200 m / h, preferably below 100 m / h, more preferably below 70 m / h, most preferably below 50 m / h. The gas loading consists essentially of hydrogen, preferably at least 60% by volume. The gas velocity at the beginning of the reactor is extremely variable, since hydrogen can also be added to intermediate feeds. However, if all hydrogen should be added at the beginning, the gas velocity is generally higher than at the reactor end. The absolute pressure in the hydrogenation is preferably in a range from 1 to 330 bar, particularly preferably in a range from 5 to 100 bar, in particular in a range from 10 to 60 bar. The temperature in the hydrogenation is preferably in a range of 60 to 300 ° C, particularly preferably from 70 to 220 ° C, in particular from 80 to 200 ° C.

In a specific embodiment, the fixed catalyst bed has a temperature gradient during the hydrogenation. Preferably, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed is maintained at a maximum of 50 K. Preferably, the temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed is maintained in a range of 0.5 to 40K, preferably in a range of 1 to 30K.

The following examples serve to illustrate the invention without limiting it in any way. EXAMPLES

The educts used and the products obtained were analyzed undiluted using standard gas chromatography and FID detector. The following quantities are GC data in area% (no water included).

The nickel-aluminum catalyst moldings used in the application examples were prepared as follows, following the examples in EP 2 764 916 A1 for the preparation of foam-form catalysts: Variant a):

0.5 g of polyvinylpyrrolidone (molecular weight: 40,000 g / mol) were dissolved in 29.5 g of demineralized water and 20 g of aluminum powder (particle size 75 μηη) was added. The resulting mixture was then shaken so that a homogeneous suspension was formed. Thereafter, a nickel foam having an average pore size of 580 μηη, a thickness of 1, 9 mm and a weight per unit area of 1000 g / m ^{2 was added} to the suspension and again shaken vigorously. The thus coated foam was placed on a paper towel and the excess suspension carefully blotted. In a rotary kiln, the thus coated foam was heated at a heating rate of 5 ° C / min to 300 ° C, then kept isothermally at 300 ° C for 30 min, further heated at 5 ° C / min to 600 ° C, for 30 min kept isothermal and further heated at 5 ° C / min to 700 ° C and kept isothermic for 30 min. The heating was carried out in a gas stream consisting of 20 NL / h nitrogen and 20 NL / h hydrogen. The cooling phase up to a temperature of 200 ° C was also in one Gas flow from 20 NL / h N2 and 20 NL / h H2. Thereafter, nitrogen was further cooled to room temperature in a stream of 100 NL / h. The foam produced in this way had a weight increase of 42% compared to the originally used nickel foam.

Variant b):

A nickel foam with an average pore size of 580 μm, a thickness of 1.9 mm and a weight per unit area of 1000 g / m ² was poured into a 1% strength by weight polyvinylpyrrolidone solution (molecular weight: 40 000 g / mol). dipped. After immersion, the foam was squeezed out on a flow cloth to remove the binder from the voids of the pores. The foam laden with the binder was then clamped in a shaker and coated with aluminum powder (particle size <75 μηη). By shaking, a uniform distribution of the powder was obtained on the surface of the open-pore foam structure and then removed excess aluminum powder. In a rotary kiln, the thus coated foam was heated at a heating rate of 5 ° C / min to 300 ° C, then kept isothermally at 300 ° C for 30 min, further heated at 5 ° C / min to 600 ° C, for 30 min kept isothermal and further heated at 5 ° C / min to 700 ° C and kept isothermic for 30 min. The heating was carried out in a gas stream consisting of 20 NL / h nitrogen and 20 NL / h hydrogen. The cooling phase up to a temperature of 200 ° C was also carried out in a gas stream of 20 NL / h N2 and 20 NL / h H2. Thereafter, nitrogen was further cooled to room temperature in a stream of 100 NL / h. The foam produced in this way had a weight increase of 36% compared to the originally used nickel foam.

The hydrogenation of 1,4-butynediol (BID) to 1,4-butanediol (BDO) is typically carried out on an industrial scale, continuously with a recycle stream, with the BID being metered into and diluted with the recycle stream. In the following, no BID solutions were used which contained more than 50% by weight of BID in water. The aqueous Bl D feedstock was prepared according to Example 1 of EP 2 121 549 A1. The feedstock was adjusted to a pH of 7.5 with sodium hydroxide solution and contained in addition to BID and water about 1 wt .-% propynol, 1, 2 wt .-% formaldehyde and a number of other by-products with proportions of well below 1 wt. -%.

The following examples were carried out in a continuous hydrogenation apparatus consisting of a tubular reactor, a gas-liquid separator, a heat exchanger and a circulation stream with a gear pump. The catalyst loadings referred to in the examples are based on the total volume of taken in the reactor built nickel-aluminum catalyst moldings.

Application Example 1

Step a):

A device with a tubular reactor with an internal diameter of 25 mm was used. 35 ml_ of a nickel-aluminum catalyst shaped body in the form of foam plates (prepared according to variant a)) was cut with a water jet cutter into round disks with a diameter of 25 mm. The disks were stacked and installed in the tubular reactor. So that the disks had no space in front of the reactor wall, a PTFE sealing ring was installed after every 5 disks.

Step b):

The reactor and the circulation stream were filled with demineralized water and then fed to a 0.5 wt .-% NaOH solution in the upflow mode and the fixed catalyst bed over a period of 2 hours at 25 ° C activated. The feed rate of the NaOH solution was 0.54 mL / min per mL of shaped catalyst body. The circulation rate was adjusted to 18 kg / h, so that a feed-to-circulation ratio of 1:16 was obtained. The flow rate of the aqueous base through the reactor was 37 m / h.

During activation, no active Raney nickel in the form of fine free particles was detected in the recycle stream or in the reactor effluent. Elemental analysis of the activating solution showed a nickel content of less than 1 ppm. The aluminum content of the activation solution was about 4.1% at the beginning of activation and decreased to 0.02% over the activation period. The maximum temperature gradient of the fixed catalyst bed during activation was 8 K.

Step c): After about 2 hours of activation, the evolution of hydrogen dropped significantly and the supply of sodium hydroxide solution was stopped and then rinsed at 40 ° C with demineralized water until a sample of circulating liquid at 20 ° C, a pH of 7.5 and a conductivity of 1 14 με / ηηη had. The flow rate of deionized water was 380 mL / h at a cycle rate of 18 kg / h, ie a feed-to-circulation ratio of 1: 47 was obtained. The flow rate of the washing solution through the reactor was 37 m / h.

Step d):

Subsequently, an aqueous solution of 0.40 g (ΝΗ4) Μθ7θ24 x 4 H2O in 20 ml of water over a period of 1 hour at 25 ° C in trickle mode supplied. After complete addition, the liquid was recirculated for 3 hours in the circulation stream at a circulation rate of 15 kg / h.

hydrogenation:

The hydrogenation was carried out with an aqueous 50 wt .-% strength Bl D solution at 155 ° C, a hydrogen pressure of 45 bar hydrogen and a catalyst loading of 0.5 kgBiD (Lkataiysatorformkör xh) at a cycle flow rate of 23 kg / h in the upflow mode , Hydrogenation yielded 94.7% BDO, 1.7% n-butanol, 0.7% methanol, 1.8% propanol and 2000 ppm 2-methylbutane-1,4-diol in the effluent over 15 days. Subsequently, the catalyst load on

1, 0 kgBiD (Lkataiysatorformkör x x h) increased at a constant cycle flow amount. The product stream consisted of (anhydrous) 94.8% BDO, 1.7% n-butanol, 0.7% methanol, 1.4% propanol, 3200 ppm 2-methylbutan-1, 4-diol and about 1% on additional secondary components.

The shaped catalyst bodies had a molybdenum gradient, which increased in the direction of flow of the hydrogenation reaction mixture through the fixed catalyst bed over the entire reactor length of 0.54 wt .-% to 1, 0 wt .-%.

Comparative Example 1 a: Step a):

A device was used with a tube reactor having an inner diameter of 25 mm as described above. 35 ml of a nickel-aluminum catalyst molding in the form of foam boards (prepared according to variant a)) was cut with a water jet cutter into round disks with a diameter of 25 mm. The disks were stacked and installed in the tubular reactor. So that the disks had no space in front of the reactor wall, a PTFE sealing ring was installed after every 5 disks. Step b):

The reactor and the recycle stream were charged with demineralized water (DI water) and then fed to a 30 wt% NaOH solution in the bulk mode and the fixed catalyst bed activated at 100 ° C over a period of 2 hours. The feed rate of the NaOH solution was 0.54 mL / min per mL of shaped catalyst body. The circulation rate was adjusted to 15 kg / h, so that a feed-to-circulation ratio of 1:13 was obtained. The flow rate of the aqueous base through the reactor was 31 m / h.

During activation, a significant amount of active Raney nickel in the form of fine free particles was detected in the recycle stream and in the effluent.

Step c):

After about 2 hours of activation, the evolution of hydrogen dropped significantly and the supply of sodium hydroxide solution was stopped and then rinsed at 40 ° C with demineralized water until a sample of circulating liquid at 20 ° C has a pH of 7.5 and had a conductivity of 467 με / ηηη. The flow rate of demineralised water was 380 mL / hr at a cycle rate of 18 kg / hr, i. an inlet to circulation ratio of 1: 47 was obtained. The flow rate of the washing solution through the reactor was 37 m / h.

Step d):

hydrogenation:

The hydrogenation was carried out with an aqueous 50 wt .-% strength Bl D solution at 155 ° C, a hydrogen pressure of 45 bar hydrogen and a catalyst loading of 0.3 kgBiD / (Lkataiysatorformkör xh) with a cycle flow rate of 23 kg / h in upflow mode. Hydrogenation gave 91.0% BDO, 3.6% n-butanol, 1.8% methanol, 2.2% propanol and 5500 ppm 2-methyl-butane-1,4-diol over 15 days. Comparative Example 1 b:

Step a): 35 ml_ of a nickel-aluminum catalyst shaped body in the form of foam sheets (prepared according to variant a)) was cut into pieces of 2 × 2 mm and introduced into the reactor likewise described in Example 1. The lower packing density resulted in a catalyst bed of 53 ml_. Step b):

The reactor and the recycle stream were charged with demineralized water (DI water) and then fed to a 30 wt% NaOH solution in the bulk mode and the fixed catalyst bed activated at 100 ° C over a period of 2 hours. The feed rate of the NaOH solution was 0.54 mL / min per mL of shaped catalyst body. The circulation rate was adjusted to 15 kg / h, so that a feed-to-circulation ratio of 1:13 was obtained. The flow rate of the aqueous base through the reactor was 31 m / h. During activation, a large amount of active Raney nickel in the form of fine free particles was detected in the recycle stream and in the effluent. Over the activation period, the amounts of nickel in the recycle stream decreased from 300 ppm to 10 ppm and the amount of aluminum in the recycle stream decreased from 3.7% to 220 ppm. Step c):

After about 2 hours of activation, the evolution of hydrogen dropped significantly and the supply of sodium hydroxide solution was stopped and then rinsed at 40 ° C with demineralized water until a sample of circulating liquid at 20 ° C has a pH of 7.5 and had a conductivity of 653 με / ηηη. The flow rate of deionized water was 380 mL / h at a circulatory rate of 15 kg / h, d. H. an inlet to circulation ratio of 1:37 was obtained. The flow rate of the washing solution through the reactor was 37 m / h. Step d):

Subsequently, an aqueous solution of 0.40 g (ΝΗ ₄ ) Μθ7θ2 ₄ x 4 H2O in 20 ml of water within 1 hour at 25 ° C in trickle mode supplied. After completing After addition, the liquid was recirculated for 3 hours in the circulation stream at a circulation rate of 15 kg / h.

hydrogenation:

The hydrogenation was carried out with an aqueous 50 wt .-% strength Bl D solution at 155 ° C, a hydrogen pressure of 45 bar hydrogen and a catalyst loading of 0.3 kgBiD / (Lkataiysatorformkör xh) with a cycle flow rate of 23 kg / h in upflow mode. Hydrogenation gave 88.5% BDO, 1.3% 2-butene-1, 4-diol, 6.0% n-butanol, 0.8% methanol, 0.5% propanol and 7600 over 2 days ppm 2-methylbutane-1, 4-diol. Complete conversion was only at a reduced catalyst loading of 0.17 kg _B iD (Lkataiysatorformkör xh) with 91, 6% BDO, 5.5% n-butanol, 0.9% methanol, 0.7% propanol and 4500 ppm 2 -Methylbutane-1, 4-diol achieved. The removed catalyst moldings after hydrogenation showed a gradient of molybdenum which increased in the direction of flow of the hydrogenation reaction mixture through the fixed catalyst bed over the entire reactor length from 0.4% by weight to 0.9% by weight. Comparative Example 1 c)

The steps a) to c) were carried out analogously to Example 1. Step d):

The catalyst was removed under argon atmosphere from the tube reactor and filled the catalyst plates in a metal basket. The metal basket with the catalyst platelets was placed in a stirred vessel with 400 ml deionized water. Thereafter, an aqueous solution of 0.40 g (ΝΗ ₄ ) Μθ7θ2 ₄ x 4 H2O in 20 ml of water was added and stirred for 3 hours at 25 ° C. Thereafter, the catalyst was re-installed under argon atmosphere in the tube reactor.

Hydrogenation: The hydrogenation was carried out with an aqueous 50% strength by weight BlD solution at 155 ° C., a hydrogen pressure of 45 bar hydrogen and a catalyst loading of 0.5 kgBiD / (Lkataiysatorformkör xh) at a circulation rate of 23 kg / h in the swamp way. Hydrogenation yielded 93.8% BDO over a period of 15 days, 2.1% n-butanol, 1, 2% methanol, 1, 8% propanol and 3500 ppm of 2-methylbutane-1, 4-diol in the discharge.

The catalyst bodies had a molybdenum content of 0.6%, which was homogeneously distributed over the catalyst bed.

Application Example 2:

Step a):

A device with a tubular reactor with an internal diameter of 25 mm was used. 600 ml of a nickel-aluminum catalyst molding in the form of foam boards (prepared according to variant a)) was cut with a water jet cutter into round disks with a diameter of 25 mm. The disks were stacked and installed in the tubular reactor. So that the disks had no space in front of the reactor wall, a PTFE sealing ring was installed after every 5 disks.

Step b):

The reactor and the recycle stream were charged with demineralized water (DI water) and then fed to a 0.5 wt% NaOH solution in the bulk mode and the fixed catalyst bed activated at 25 ° C over a period of 7 hours. The feed rate of the NaOH solution was 0.14 mL / min per mL of shaped catalyst. The circulation rate was adjusted to 19 kg / h, so that a feed-to-circulation ratio of 1: 4 was obtained. The flow rate of the aqueous base through the reactor was 39 m / h. The maximum temperature gradient of the fixed catalyst bed, measured between reactor inlet and reactor outlet during the activation was 15 K.

During activation, no active Raney nickel in the form of fine free particles was detected in the recycle stream or in the reactor effluent. Elemental analysis of the activating solution showed a nickel content of less than 1 ppm. The aluminum content of the activation solution was about 4.5% at the beginning of activation and decreased to 0.7% over the activation period.

Step c): After 7 hours of activation, the evolution of hydrogen dropped significantly and the supply of caustic soda was stopped and then rinsed at 40 ° C demineralized water until a sample of recirculated liquid at 20 ° C has a pH of 7.5 and a conductivity of 5 με / ηηη had. The flow rate of deionized water was 1 L / h at a circulation rate of 15 kg / h, ie, a feed-to-circulation ratio of 1:15 was obtained. The flow rate of the washing solution through the reactor was 31 m / h.

Step d):

Subsequently, an aqueous solution of 6.86 g (ΝΗ4) Μθ7θ24 x 4 H2O in 300 ml of water over a period of 7 hours at 25 ° C in trickle mode supplied. After complete addition, the liquid was recirculated overnight in the circulation stream at a circulation rate of 15 kg / h.

hydrogenation:

The hydrogenation was carried out with an aqueous 50 wt .-% strength Bl D solution at 155 ° C, a hydrogen pressure of 45 bar hydrogen and different catalyst loads and cycle flow amounts, as shown in Table 1. The CO concentrations are given in ppm by volume at the reactor inlet and outlet.

Table 1 :

5 BDO = 1, 4-butanediol

MeOH = methanol

BuOH = n-butanol

PrOH = n-propanol

MBDO = 2-methylbutane-1, 4-diol

10 BED = 2-butene-1, 4-diol

The expanded catalyst bodies showed after hydrogenation a molybdenum gradient in the flow direction over the entire reactor length of 0.4 wt .-% to 1, 0 wt .-%.

Use Example 3: Steps a) -d): Analogously to Application Example 1, 35 ml of a nickel-aluminum catalyst molding (prepared according to variant b)) were introduced into a tubular reactor having an internal diameter of 25 mm, activated and washed with demineralized water. During the doping, in turn, an aqueous solution of 0.40 g (ΝΗ4) Μθ7θ24 x 4 H2O in 20 ml of water was added over a period of 1 hour at 25 ° C and pumped in the circulation in the upflow mode. Thereby, a molybdenum gradient was obtained, which decreases in the flow direction of the reaction mixture of the hydrogenation through the fixed catalyst bed. After complete addition, the liquid was recirculated for 3 hours in the circulation at a circulation rate of 15 kg / h. hydrogenation:

The hydrogenation of undiluted n-butyraldehyde (n-BA) was carried out at 140 ° C, 40 bar hydrogen pressure and a catalyst loading of 1, 5 kg _n -BA / (Lkataiysatorformkör xh) performed with a loop rate of 23 kg / h in the upflow mode. Hydrogenation afforded 99.6% n-butanol, 0.08% butyl acetate, 0.01% dibutyl ether, 0.01% butyl butyrate, 0.07% ethylhexanediol and 0.03% acetal over a period of 8 days. The removed catalyst moldings after hydrogenation showed a molybdenum gradient which decreased in the direction of flow of the hydrogenation reaction mixture through the fixed catalyst bed over the entire reactor length from 1.0% by weight to 0.3% by weight.

Claims

claims

1 . Process for providing a fixed catalyst bed containing monolithic shaped catalyst bodies or consisting of monolithic shaped catalyst bodies containing at least one first metal selected from Ni, Fe, Co,

Cu, Cr, Pt, Ag, Au and Pd, and containing at least one second component selected from Al, Zn and Si, wherein the fixed catalyst bed for activating a treatment with a maximum of 3.5 wt .-%, aqueous base and contacting the fixed catalyst bed obtained after activation with a dopant having at least one promoter element different from the first metal and the second component.

2. The method of claim 1, wherein introducing into a reactor a fixed catalyst bed containing monolithic shaped catalyst body or consists of monolithic catalyst moldings containing at least one first metal selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, and containing at least one second component selected from Al, Zn and Si, the catalyst fixed bed for activating a treatment with a maximum of 3.5 wt .-%, aqueous base, optionally in step b) subjecting the activated fixed catalyst bed to a treatment with a wash medium selected from water, C 1 -C 4 alkanols and mixtures thereof, the fixed catalyst bed obtained after activation in step b) or after the treatment in step c), contacting with a dopant which has at least one element selected from the first metal and the second component of the catalyst used in step a) Torformkörper is different.

Method according to one of the preceding claims, wherein the fixed catalyst bed in the flow direction has a gradient with respect to the concentration of the promoter elements.

4. The method according to any one of the preceding claims, wherein the monolithic shaped catalyst bodies used, based on the entire molded body, have a smallest dimension in a direction of at least 1 cm, preferably at least 2 cm, in particular at least 5 cm.

5. The method according to any one of the preceding claims, wherein the catalyst fixed bed during activation has a temperature gradient and the

Temperature difference between the coldest point of the fixed catalyst bed and the warmest point of the fixed catalyst bed at a maximum of 50 K, preferably at a maximum of 40 K, in particular at a maximum of 25 K is maintained.

6. The method according to any one of the preceding claims, wherein the aqueous base used for activation is at least partially conducted in a liquid circulation stream, wherein the ratio of recycled aqueous base to freshly supplied aqueous base in a range of 1: 1 to 1000: 1 , preferably from 2: 1 to 500: 1, in particular from 5: 1 to 200: 1, is located.

7. The method according to any one of the preceding claims, wherein the monolithic shaped catalyst bodies are in the form of a foam, wherein to provide the monolithic shaped catalyst body: a1) provides a metal foam molded body containing at least one first metal, which is selected from Ni, Fe, Co, Cu, Cr, Pt, Ag, Au and Pd, a2) applies to the surface of the metal foam molded body at least a second component containing an element selected from Al, Zn and Si, and a3) by alloying the formed in step a2) metal foam molding forms an alloy at least on a part of the surface.

8. The method according to any one of the preceding claims, wherein the first metal contains Ni or consists of Ni and wherein the second component contains Al or consists of Al.

9. The method according to any one of the preceding claims, wherein the dopant contains at least one promoter element which is selected from Ti, Ta, Zr, V,

Cr, Mo, W, Mn, Re, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Ce and Bi, preferably under Ti, Ce, V, Mo, W, Mn, Re, Ru, Rh, Ir, Pt and Bi.

10. The method according to any one of the preceding claims, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of catalyst form containing nickel and aluminum and which are doped with Mo and wherein the fixed catalyst bed in the flow direction has a gradient with respect to the Mo concentration.

A reactor containing a fixed catalyst bed obtainable by a process as defined in any one of claims 1 to 10. 12. A process for the hydrogenation of hydrogenatable organic compounds, in particular organic compounds containing at least one carbon-carbon double bond, carbon-nitrogen double bond, carbon-oxygen double bond, carbon-carbon triple bond, carbon-nitrogen triple bond or nitrogen Oxygen double bond, in the presence of an activated fixed catalyst bed, obtainable by a process as defined in any one of claims 1 to 10, or in a reactor as defined in claim 11.

A process as claimed in claim 12 for the hydrogenation of 1,4-butynediol to give 1,4-butanediol, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of shaped catalyst bodies which contain nickel and aluminum and which are doped with Mo and where the concentration of molybdenum in the flow direction the reaction medium of the hydrogenation reaction increases.

A process according to claim 12 for the hydrogenation of 4-butyraldehyde to give n-butanol, wherein the fixed catalyst bed contains shaped catalyst bodies or consists of shaped catalyst bodies containing nickel and aluminum doped with Mo and wherein the concentration of molybdenum in the direction of flow of the reaction medium of the hydrogenation reaction decreases.

Method according to one of claims 12 to 14, wherein the hydrogenation is carried out according to the inventive method in the presence of CO.