DE10241266A1 - Production of 7-17C aliphatic alcohols, useful as solvents and precursors for detergents and plasticizers, comprises cobalt catalyzed hydroformylation of 6-16C olefins and oxidative decomposition of the catalyst in the presence of water - Google Patents

Abstract

Production of 7-17C aliphatic alcohols comprises cobalt catalyzed hydroformylation of 6-16C olefins and oxidative decomposition of the active cobalt catalyst in the hydroformylation outlet by reaction with oxygen containing gases whereby all the process steps are carried out in the presence of water. A process for the production of 7-17C aliphatic alcohols comprises: (a) cobalt catalyzed hydroformylation of 6-16C olefins; (b) oxidative decomposition of the active cobalt catalyst in the hydroformylation outlet by reaction with oxygen containing gases; (c) separation of the mixture from (B) to form a cobalt salt containing aqueous phase and an aliphatic aldehyde containing organic phase; (d) distillation of the organic phase to form a low b.pt. fraction containing unreacted olefins and an aldehyde containing sump fraction and; (e) hydrogenation of the aldehyde containing sump fraction whereby all the process steps are carried out in the presence of water.

Description

The invention relates to a method for the production of alcohols by single or multi-stage hydroformylation separation of olefins or olefin mixtures in the presence of a cobalt catalyst of the catalyst and subsequent Hydrogenation of the separated hydroformylation products, all Process steps are carried out in the presence of water.

higher Alcohols, especially those with 7 to 17 carbon atoms, can be known by catalytic hydroformylation (also called oxo reaction) the poorer by one carbon atom Olefins and by subsequent Hydrogenation of the aldehydes formed. The alcohols can as a solvent or as a preliminary stage for Detergents or plasticizers can be used.

Process for the hydroformylation of A large number of olefins have been described in the literature. The vote of the catalyst system and the optimal reaction conditions for the hydroformylation are of reactivity depending on the olefin used. The influence of the structure of the olefin used on its reactivity in one Hydroformylation reaction is e.g. B. by J. FALBE, "New Syntheses with Carbon Monoxide ", Springer Verlag, 1980, Berlin, Heidelberg, New York, page 95 ff.

Technical olefin mixtures, which as Educts for The hydroformylation reaction used often contain Olefin isomers of various structures with different Branches of branching, different positions of the double bond and Olefins of different molar masses. This applies in particular to olefin mixtures, by the di-, tri- or further oligomerization of olefins with 2 to 8 carbon atoms or other easily accessible higher olefins or by cooligomerization of the olefins mentioned have arisen. As examples of typical Olefin mixtures that are technically for the hydroformylation are relevant are tri- and tetrapropene and also called di-, tri- and tetrabutenes.

In a technically carried out hydroformylation is it desirable in addition to high sales to achieve high selectivity in order to achieve an optimal To ensure utilization of the raw material. In order to achieve a high turnover, you have to react slowly Olefins often have a relatively long reaction time and / or higher reaction temperatures to be accepted. In contrast, more reactive olefins are used the same reaction conditions in a much shorter time converted to the aldehydes. In the common hydroformylation this leads to mixtures of olefins of different reactivity to the fact that it takes relatively long reaction times to achieve a sufficient To achieve sales of olefins that are more difficult to oxidize. From However, the aldehydes which are more easily convertible olefins become relative quickly formed and then lie next to the more difficult hydroformylatable Olefins in the reactor. this leads to to undesirable Side and subsequent reactions the aldehydes, e.g. B. for hydrogenation, condensation reactions and for the formation of acetals and hemiacetals. Mainly because of the different Reactivity of Olefin isomers are difficult to undergo in a hydroformylation reaction high sales and at the same time high selectivities to achieve.

In addition to the unfavorable impact on selectivity there are two other aspects against common hydroformylation speak of olefin mixtures in one step up to high sales. On the one hand, the relatively long response times require one predetermined capacity or reactor output of relatively large reactor volumes. This is particularly disadvantageous because it is in hydroformylation processes are processes that are Pressure expire and the investment costs for pressure reactors with their Size exponential increase. On the other hand, you are in control of the process the wished Product properties of the aldehydes, e.g. determined by the ratio of linear (n) to branched (i) aldehydes (n / i ratio), limited.

As a solution to the different reactivities multi-stage reaction procedures - with or without an intermediate partition of the products formed in one reaction stage - developed.

In GB 1 387 657 describes a two-stage hydroformylation in which the reaction product of the first stage is discharged in gaseous form and, after the aldehydes or alcohols have been condensed, the exhaust gas from the first stage, which contains unreacted olefins, is partly returned to the first stage and partly to one second reactor is passed.

Another variant of a two-stage hydroformylation is in DE 32 32 557 described. In the first stage, the olefins are hydroformylated using a cobalt catalyst with conversions of 50 to 90%, the cobalt catalyst is separated from the reaction mixture and the aldehydes formed, together with the unreacted olefins, are introduced into a second hydroformylation stage. The ligand-modified cobalt catalyst used here not only effects the hydroformylation of the olefins, but also a hydrogenation of the aldehydes to the alcohols.

• a) in einem Hydroformylierungsschritt bis zu einem Umsatz von 20 bis 98 % hydroformyliert werden,
• b) der Katalysator aus dem so erhaltenen flüssigen Reaktoraustrag entfernt wird,
• c) das so erhaltene flüssige Hydroformylierungsgemisch in eine Leichtsiederfraktion, enthaltend Olefine und Paraffine und eine Sumpffraktion, enthaltend Aldehyde und/oder Alkohole getrennt wird,
• d) die in der Leichtsiederfraktion enthaltenden Olefine in weiteren Verfahrensstufen, umfassend die Verfahrensschritte a, b und c umgesetzt werden und die Sumpffraktionen der Verfahrensschritte c) aller Verfahrensstufen vereinigt werden.

In DE 100 34 360 describes a process for the multistage cobalt- or rhodium-catalyzed hydroformylation of olefins having 6 to 24 carbon atoms to alcohols and / or aldehydes, wherein the olefins

• a) hydroformylated in a hydroformylation step up to a conversion of 20 to 98%,
• b) the catalyst is removed from the liquid reactor discharge thus obtained,
• c) the liquid hydroformylation mixture thus obtained is separated into a low boiler fraction containing olefins and paraffins and a bottom fraction containing aldehydes and / or alcohols,
• d) the olefins contained in the low boiler fraction are reacted in further process steps, comprising process steps a, b and c, and the bottom fractions of process steps c) of all process steps are combined.

This method is preferred in this way applied that the liquid Reactor discharge of the hydroformylation steps a) a homogeneous liquid phase is. The cobalt or rhodium catalysts are preferably used so that they are homogeneous in the liquid reactor discharge the hydroformylation steps a) are solved.

In EP 1 057 803 discloses a two-step process for the preparation of alcohols from olefins or olefin mixtures. In the first reaction stage, 50 to 90% of the feed olefin is hydroformylated in the presence of a cobalt catalyst. After the catalyst has been separated off, the unreacted olefins are separated off by distillation from the reaction discharge and the separated olefins are reacted in the second hydroformylation reactor. The hydroformylation products from both stages can be hydrogenated to the corresponding alcohols. In both reaction stages, Co ₂ (CO) ₈ or HCo (CO) _{4 is} used as the catalyst, which is generated outside the hydroformylation reactors. The cobalt catalyst is removed from the reaction mixture of the hydroformylation before further processing by extraction with a base.

Disadvantages of this process are the complicated work-up of the catalyst and the unsatisfactory yield. According to Example 5, a maximum yield of C ₉ alcohol mixture of approximately 83% can be obtained from a butene dimer mixture.

A hydroformylation process in which the production of the active cobalt catalyst from an aqueous cobalt salt solution, extraction of the active cobalt catalyst into the organic phase and hydroformylation takes place simultaneously in the same reactor is described, for example, in DE 196 54 340 described.

In most cobalt-catalyzed hydroformylation processes known from the literature, the cobalt catalyst (HCo (CO) ₄ or Co ₂ (CO) ₈ ) is oxidatively destroyed after the hydroformylation step. This is usually done by reacting the hydroformylation discharge with air in the presence of an aqueous phase, the cobalt (II) salts thus produced being extracted into the aqueous phase. The aqueous phase is separated off, for. B. by decanting in a phase separation container or in other suitable facilities. After separation from the aqueous phase, the organic phase is fed to a catalytic hydrogenation.

The residual amount of cobalt catalyst remaining in the organic phase is generally less than 5 ppm cobalt (calculated as metal). These residual amounts of cobalt can have negative effects on the hydrogenation as well as on the distillative workup over the course of the operating time. As in DE 102 27 995.0 described, these residual cobalt contents can be reduced to an cobalt content of less than 0.1 ppm by extraction with water.

The selectivity of a manufacturing process of alcohols from olefins is largely determined by the hydroformylation step, but also from the rest Process steps such as catalyst separation, distillation and Hydrogenation determined.

The present invention was the Task based on a process for the preparation of higher oxo alcohols (with more than 6 carbon atoms) from the corresponding olefin mixtures to provide that high sales with high selectivities connects, is characterized by high space-time yields and one Product with a high proportion of terminally hydroformylated olefins or after the hydrogenation of the aldehydes thus obtained, the corresponding Alcohol supplies.

It was found that through a A process for the preparation of alcohols from olefins comprising the Steps of cobalt-catalyzed hydroformylation of the olefins, separation of the catalyst and / or the unreacted olefins and subsequent hydrogenation the product fraction thus obtained, particularly good selectivities achieved can be if all process steps are carried out in the presence of water.

• a) Kobaltkatalysierte Hydroformylierung von Olefinen mit 6 bis 16 Kohlenstoffatomen,
• b) Oxidative Zersetzung des aktiven Kobalt-Katalysators im Hydroformylierungsaustrag durch Umsetzung mit Sauerstoff-haltigen Gasen
• c) Trennung des Gemisches aus b) in eine Kobaltsalz enthaltende wässrige und eine die aliphatischen Aldehyde enthaltende organische Phase,
• d) Destillative Auftrennung der organischen Phase in eine Leichtsiederfraktion, enthaltend nicht umgesetzte Olefine und eine Aldehyd-haltige Sumpffraktion.
• e) Hydrierung der Aldehyd-haltigen Sumpffraktion, dadurch gekennzeichnet, dass alle Verfahrensschritte in Gegenwart von Wasser durchgeführt werden.

The present invention therefore relates to a process for the preparation of aliphatic alcohols having 7 to 17 carbon atoms by one or more reaction stages, each comprising the steps

• a) cobalt-catalyzed hydroformylation of olefins having 6 to 16 carbon atoms,
• b) Oxidative decomposition of the active cobalt catalyst in the hydroformylation output by reaction with oxygen-containing gases
• c) separation of the mixture from b) into an aqueous cobalt salt and an aliphatic Al organic phase containing dehyde,
• d) Distillative separation of the organic phase into a low boiler fraction containing unreacted olefins and an aldehyde-containing bottom fraction.
• e) hydrogenation of the aldehyde-containing bottom fraction, characterized in that all process steps are carried out in the presence of water.

The method steps preferably have the water contents defined below. The pH water is preferred in reaction steps a), b), c), d) also in e) less than or equal to 7.

Will the inventive method executed in one stage, step d) can optionally be omitted. In this case the in step c) separated organic phase directly from the hydrogenation e fed.

The method according to the invention can be used with respect to anyone Process stage and each process step continuously or carried out discontinuously become. All process steps are preferably carried out continuously. It several process variants are possible.

Version 1:

In this process variant go through at least two reaction stages, the step d) separated low boiler fraction in step a) of the following Passed reaction stage and that in steps d) of all reaction stages separated aldehyde-containing bottom fractions in a common step e) are hydrogenated. In this process variant, the Follow steps a), b), c) and d) successively and only the hydrogenation the aldehyde-containing bottom fraction e) takes place together for all reaction stages.

The process according to variant 1 is shown in block diagram in 1 played. In the first hydroformylation reactor 1 become the olefin mixture 3 , the synthesis gas 2 (Carbon monoxide and hydrogen) as well as an aqueous solution of a cobalt compound or cobalt catalyst and water. The hydroformylation mixture thus obtained 5 is relaxed to 30 to 15 bar and after decobbing with water and air 7 in the first catalyst separation ( 8th ) of cobalt compound ( 4 ) exempt. Before catalyst separation 8th becomes excess syngas 6 deducted. The aqueous phase containing cobalt salts is passed into the first hydroformylation reactor, if appropriate after discharging a small substream and after supplementing it with fresh catalyst 1 recycled. With catalyst here are precursors of catalysts such. B. cobalt (II) salt solutions. The organic phase freed from the catalyst 9 is in a separation stage 10 into a hydrocarbon fraction 11 , which consists mainly of unreacted olefins, and crude aldehyde 12 Cut. The low boilers 11 , Synthesis gas 13 and an aqueous solution of a cobalt compound or an already formed cobalt catalyst and water 16 are in the second hydroformylation reactor 14 brought in. The hydroformylation mixture 15 from the second hydroformylation reactor 14 is relaxed to 30 to 15 bar and after decobbing with water and air 18 in the second catalyst separation 19 from the catalyst 16 freed. Before catalyst separation 19 becomes excess syngas 17 deducted. The separated catalyst 16 is, optionally after removal of a small partial stream and after supplementation with fresh catalyst, in the second hydroformylation reactor 14 recycled. The decatalyzed hydroformylation mixture 20 can in the separation stage 21 into a hydrocarbon fraction 22 , which consists mainly of saturated hydrocarbons, and crude aldehyde 23 be separated. If necessary, part of the hydrocarbon fraction 22 in the reactor 14 be reduced. (Lead in 1 not drawn).

Before and / or in the hydrogenation reactor 24 can optionally add additional water 27 A further embodiment of this process variant is that the decobolded hydroformylation mixture 20 without separation in the separation stage 21 along with the crude aldehyde 12 from the first hydroformylation stage of the hydrogenation unit 24 is fed (line 25 ). The Rohaldehyde 12 and 23 respectively. 12 and 20 are in the hydrogenation reactor 24 with hydrogen to the raw alcohol 26 hydrogenated, which can optionally be worked up to pure alcohol in a distillation, not shown.

Variant 2

In this process variant, two reaction stages are carried out, the low boilers separated off in step d) of the first reaction stage being passed to step a) of the second reaction stage and the organic discharge from steps c) of both stages being passed to step d) of the first reaction stage. Here each reaction stage has a hydroformylation step a), a decobbing step b) and a catalyst separation step c), the separated catalyst phase being fed back into the respective hydroformylation step. The separated organic phase is separated in a separation step d) common to both reaction stages into a low boiler fraction and an aldehyde-containing bottom fraction. The low boiler fraction thus obtained is separated into the hydroformylation step a) of the second reaction stage Bottom fraction passed into a common hydrogenation step e).

The block diagram of this process variant is in 2 shown. In the first hydroformylation reactor 1 become the olefin mixture 3 , the synthesis gas 2 (Carbon monoxide and hydrogen) and an aqueous solution of a cobalt compound or cobalt catalyst together with water. The hydroformylation mixture thus obtained 5 is relaxed to 50 to 15 bar and after decobbing with water and air 7 in the first catalyst separation 8th freed from cobalt compounds. Before catalyst separation 8th becomes the excess syngas 6 deducted. Aqueous phase containing the cobalt salts 4 is, optionally after discharge of a small substream and after addition of fresh catalyst, in the first hydroformylation reactor 1 recycled. The decobtained organic phase 9 is in the separation stage 10 directed. There it is together with the decobtained hydroformylation mixture 20 from the second hydroformylation reactor 14 into a fraction 11 , which contains the unreacted olefins and inert paraffins, and crude aldehyde 21 Cut. The hydrocarbon fraction 11 after a partial flow has been discharged 12 for the separation of saturated hydrocarbons (paraffins) and other non-olefinic compounds, together with synthesis gas 13 and an aqueous solution of a cobalt compound or a mixture of cobalt catalyst and water 19 in the second hydroformylation reactor 14 guided. The hydroformylation mixture 30 is relaxed to 15 bar and after decobbing with water and air 17 in a second catalyst separation 18 from the catalyst 19 freed. Before catalyst separation 18 becomes the excess syngas 16 deducted. The separated catalyst 19 is, optionally after discharge of a small substream and after supplementation with fresh catalyst, in the second hydroformylation reactor 14 recycled. The decobtained second hydroformylation mixture 20 with the hydroformylation mixture 9 the first stage, as already mentioned, in the separation stage 10 fed. The crude aldehyde 21 is in the hydrogenation unit 22 with hydrogen to raw alcohol 23 be hydrogenated. This alcohol can be worked up to the pure alcohol in a distillation (not shown).

Before and / or in the hydrogenation reactor 22 can optionally add additional water 24 be fed.

The saturated hydrocarbons can be discharged instead of via the partial flow 12 also by working up a partial stream of the decobtained hydroformylation product 20 take place (not shown). Technically, this is done, for example, by separating this substream into low-boilers, which are discharged, and aldehydes, which are separated into the decobtained hydroformylation mixture 20 or the crude aldehyde 21 be returned, realizable.

This embodiment of the invention has for every Process step a hydroformylation step a), a decobalization step b) and a catalyst separation step c), the combined liquid Hydroformylation mixtures, in a common distillation step d) separated into low boiler and bottom fractions, with the proviso that the catalyst separated off in steps b) and c) directly or after working up in the hydroformylation step a) of the respective Process stage is returned.

Variant 3

In a further variant of the method according to the invention two reaction stages are run through, the steps in step d) the first reaction stage separated low boilers in the step a) the second reaction stage and steps b), c) and e) for both reaction stages are carried out together. This is where the Working up the hydroformylation mixtures from process step a) both reaction stages in common steps b), c) and e).

This variant of the method according to the invention is shown in 3 shown. In the first hydroformylation reactor 1 become the olefin mixture 3 , the synthesis gas 2 (Carbon monoxide and hydrogen) and an aqueous solution of a cobalt compound 4 fed. The hydroformylation mixture thus obtained 5 together with the hydroformylation mixture 18 from the second hydroformylation reactor 17 as a combined hydroformylation output relaxed to 30 to 15 bar and after the decobbing with water and air 7 in the catalyst separation 8th from the catalyst 9 freed. Before catalyst separation 8th becomes the excess syngas 6 deducted. A mixture is obtained 10 , which contains the aldehydes, alcohols and unreacted olefins formed. The catalyst 9 is, optionally after removal of a subset and supplemented with fresh catalyst, in the two sub-streams 4 and 16 divided. partial flow 4 is in the first hydroformylation reactor 1 and partial flow 16 in the second hydroformylation reactor 17 scaled back. The decobtained hydroformylation output 10 is in the separation stage 11 into the hydrocarbon fraction 12 and the crude aldehyde 14 separated. The hydrocarbon fraction 12 , which contains the unreacted olefins, optionally after removal of a subset 13 for the separation of saturated hydrocarbons or other non-olefinic compounds, together with synthesis gas 15 and aqueous solution of a cobalt compound or a mixture of cobalt catalyst and water 16 in the second hydroformylation reactor 17 initiated. The crude aldehyde 14 is in the hydrogenation unit 19 with hydrogen to raw alcohol 20 be hydrogenated. This, in turn, cannot represent one distillation can be worked up to pure alcohol.

Before and / or in the hydrogenation reactor 19 can, as in variants 1 and 2, optionally additional water 21 be fed.

With variant 3 it is also possible to discharge saturated hydrocarbons by separately working up a partial stream of the hydroformylation mixture 18 to be carried out, for example by separating off the low boilers by distillation. This embodiment of the process according to the invention is characterized in that the combined reactor discharges of all hydroformylation steps a) pass through only one decobbing step b) and one catalyst separation step c) and one olefin separation step d), with the proviso that the process steps b) and c) separated catalyst solution directly or after workup and the hydroformylation steps a) of the individual process steps is returned.

Variants 1 to 3 used here for procedures have been described with two hydroformylation stages apply mutatis mutandis to processes with more than two hydroformylation stages.

The following are the reaction steps a) -e) explained in more detail.

a) Hydroformylation reaction

The reactors in which the hydroformylation carried out will, can be the same or different in all process stages. Examples for usable Reactor types are bubble columns, Loop reactors, jet nozzle reactors, stirred reactors and tubular reactors, partly cascaded and / or with internals can be provided.

The starting materials for the process according to the invention are olefins or mixtures of olefins having 6 to 16 carbon atoms, in particular having 8 to 12 carbon atoms and having terminal or internal CC double bonds. The mixtures can consist of olefins of the same, similar (± 2) or significantly different (> ± 2) C number. Examples of olefins which can be used either in pure form, in an isomer mixture or in a mixture with other olefins with a different C number as starting material are: 1-, 2- or 3-hexene, 1-heptene, linear heptenes with internal double bond (2-heptene, 3-heptene, etc.), mixtures of linear heptenes, 2- or 3-methyl-1-hexene, 1-octene, linear octenes with internal double bond, mixtures of linear octenes, 2- or 3-methylheptene, 1-nonen, linear nonenes with an internal double bond, mixtures of linear nonenes, 2-, 3- or 4-methyloctenes, 1-, 2-, 3-, 4- or 5-decene, 2-ethyl-1-octene, 1- Dodecene, linear dodecenes with internal double bond, mixtures of linear dodecenes, 1-tetradecene, linear tetradecenes with internal double bond, mixtures of linear tetradecenes, 1-hexadecene, linear hexadecenes with internal double bond, mixtures of linear hexadecenes. Suitable starting materials are also the mixture of isomeric hexenes (dipropen) obtained in the dimerization of propene, the mixture of isomeric octenes (dibutene) obtained in the dimerization of butenes, the mixture of isomeric nonenes (tripropen) obtained in the trimerization of propene, the Tetramerization of propene or the trimerization of butenes, a mixture of isomeric dodecenes (tetrapropene or tributes), the hexadecene mixture (tetrabutene) resulting from the tetramerization of butenes and oligins produced by cooligomerization of olefins with different C numbers (preferably 2 to 4), if necessary after separation by distillation into fractions with the same or similar (± 2) C number. Furthermore, olefins or olefin mixtures which have been produced by Fischer-Tropsch synthesis can be used. In addition, olefins produced by olefin metathesis or by other technical processes can be used. Preferred starting materials are mixtures of isomeric octene, nonenes, dodecenes or hexadecenes, ie oligomers of lower olefins, such as n-butenes, isobutene or propene. Other educts that are also very suitable are oligomers of C ₅ olefins.

In principle, there are three process variants for the oligomerization of butenes to mixtures essentially containing C ₈ olefins. Oligomerization over acidic catalysts has long been known. B. zeolites or phosphoric acid can be used on supports. This gives isomer mixtures of branched olefins, which are essentially dimethylhexenes (WO 92/13818). Another method that is practiced worldwide is oligomerization with soluble Ni complexes, known as the DIMERSOL method (see J. Schulze, M. Homann, "C ₄ Hydrocarbons and Derviates", Springer-Verlag, Berlin, Heidelberg 1989, p. 69 and B. CORNILS, WA HERRMANN, "Applied Homogeneous Catalysis with Organic Metallic Compounds"; Vol. 1 & 2, VCH, Weinheim, New York 1996). The third process variant is the oligomerization on nickel fixed bed catalysts; one of these methods is the OCTOL process (Hydrocarbon Process., Int. Ed. (1986) 65 (2nd Sect. 1) pages 31-33).

For the production according to the invention of a C ₉ alcohol mixture, which is particularly suitable for the preparation of plasticizers, a C ₈ olefin mixture, which was obtained from linear butenes by the OCTOL process, is preferably used.

The hydroformylation of the olefins takes place in the process according to the invention in the presence of cobalt catalysts, preferably unmodified catalysts such as HCo (CO) ₄ and / or Co ₂ (CO) ₈ and water. It Both pre-formed catalyst or a catalyst precursor, such as a cobalt compound, from which the actual catalyst is formed in the reactor, can be fed into the hydroformylation reactor.

When the finished active catalyst (e.g. HCo (CO) ₄ and / or Co ₂ (CO) ₈ ) is used, water, olefin, catalyst and synthesis gas are fed to the reactor. Water can be dispersed in the olefin before the reactor, for example by using a static mixer. However, it is also possible to mix all components only in the reactor.

The amount of water in the hydroformylation reactor can be varied in a wide range. By adjusting the ratio of Water and olefin and the reaction parameters, for example temperature, can be in liquid Hydroformylation discharge water can be homogeneously dissolved or additionally dispersed.

In the process according to the invention, the formation of the catalyst (HCo (CO) ₄ and / or Co ₂ (CO) ₈ ) in situ in the hydroformylation reactor is preferred. Such a process is e.g. 8th in DE 196 54 340 described. According to this process, the starting materials, such as the cobalt salt solution, the organic phase and the synthesis gas, are introduced simultaneously, preferably with the aid of a mixing nozzle, into the reactor in cocurrent from below.

Preferred cobalt compounds are Cobalt salts such as formates, acetates or salts of carboxylic acids, the water soluble are used. Tried and tested has cobalt acetate, which is called watery solution with a cobalt content of 0.5 to 3 mass%, preferably of 0.8 to 1.8 mass%, calculated as metal, is used. On another preferred application for the Production of the catalyst is the aqueous cobalt salt solution during decobalization (steps b and c). In the solutions used, too more than one cobalt compound may be included.

The one in the hydroformylation reactor desired The amount of water can be introduced with the cobalt salt solution, the Concentration can be varied within a wide range. However, it is also possible, next to the cobalt salt solution additional Feed water.

Particular importance is attached to the cobalt-catalyzed process of dosing the starting materials added to the reactor. The dosing device must be a good one Ensure phase mixing and the generation of the largest possible phase exchange area. Also advantageous is the reactor space of the hydroformylation reactors by installing 1 to 10, preferably 2 to 4, perpendicular to Flow direction of the Reactants and Product flow arranged to subdivide perforated plates. By the reactor cascading becomes backmixing compared to simple bubble column greatly reduced and the flow behavior approximated that of a tubular actuator. This procedural measure has the consequence that both the yield and the selectivity of the hydroformylation be improved.

Precise information on hydroformylation steps can be found in DE 199 39 491 and DE 101 35 906 be removed.

So according to DE 199 39 491 a partial stream of the liquid mixed phase (aqueous cobalt salt solution / organic phase) is drawn off from the lower part of the reactor and fed into a higher point of the reactor.

To DE 101 35 906 the level of an aqueous phase is kept constant in the hydroformylation reactor, the concentration of cobalt compounds (calculated as metallic cobalt) in this aqueous bottom phase being in the range from 0.4 to 1.7% by mass.

In the hydroformylation steps can same or different conditions are set, preferred are temperatures from 100 to 250 ° C and pressures from 100 to 400 bar. special proven have temperatures of 140 to 210 ° C and synthesis gas pressures of 200 to 300 bar. The volume ratio from carbon monoxide to hydrogen in the synthesis gas is generally between 2: 1 and 1: 2, especially in the volume ratio of 1: 1.5. The synthesis gas is advantageously in excess, for example up to to three times the stoichiometric Amount used.

With multi-stage process variants the hydroformylation is advantageous in the first process stage, in which the more reactive olefins are reacted at temperatures between 140 to 195 ° C, preferably at 160 to 185 ° C carried out. In this process stage, olefin conversions between 20 and 95% are preferred targeted between 50 and 80%.

In the liquid hydroformylation discharge is the concentration of cobalt compounds (calculated as metallic Cobalt) 0.01 to 0.5 mass%, in particular 0.02 to 0.08 mass % (based on the sum of the organic and aqueous phase).

Because of the different possibilities the water addition is the water content in the entry of the hydroformylation reactor difficult to determine. In the following, therefore, information about the Water content made in the discharge of the reactor, the water content in the reactor discharge practically synonymous with the water content the liquid Phase during the reaction is.

The water concentrations in the liquid hydroformylation outputs can between 0.1 to 10% by mass, in particular between 0.5 to 5% by mass lie. The water content of the hydroformylation outputs of the individual Levels are the same or different. The water is preferably in the liquid hydroformylation outputs homogeneously solved.

b) Oxidative decomposition of the active cobalt catalyst (decobolding)

The product discharges are after leaving the Hydroformylation reactors relaxed to 15 to 30 bar and into the each separation stage c) including decobolding b). in the Decobbing step b) is the product discharge (liquid phase) the hydroformylation reaction a) in the presence of an aqueous Cobalt (II) salts containing carboxylic acid solution ("process water") Gases containing oxygen, especially air or oxygen Temperatures from 130 to 190 ° C implemented and thus oxidatively freed from cobalt-carbonyl complexes. The decobalization methods are well known and in the literature detail, such as B by J. FALBE, in “New Syntheses with Carbon Monoxide ", Springer Verlag (1980), Berlin, Heidelberg, New York, page 158 ff.

Decobolding b) is preferred in one with packing, like e.g. Raschig rings, filled pressure vessels, in if possible high phase exchange area is generated, carried out.

c) separation of organic and aqueous phase

The practically cobalt-free organic Product phase is in a downstream separation container, i.e. H. the actual separation stage c), at temperatures of 50 to 90 ° C from the aqueous Phase separated. For the Phase separation is preferably carried out using horizontal separation containers Internals used. The watery Phase, the "process water", which is the extracted back from the organic Contains phase recovered cobalt in the form of cobalt acetate / formate, aside from the part that goes into the decobalter as process water is returned entirely or after a small portion has been discharged into the oxo reactor of the respective process stage and preferably as a starting material for the in-situ preparation of the cobalt-catalyst complexes used.

Optionally, part of the excess formic acid can be removed before the process water is returned to the hydroformylation reactor. This can be done for example by distillation. Another possibility is to decompose part of the formic acid, for example catalytically, as in DE 100 09 207 described.

It is also possible to prepare the actual hydroformylation catalyst (Co ₂ (CO) ₈ and / or HCo (CO) ₄ ) from the cobalt salt solution obtained in the decobalization by precarbonylation and to return it to the hydroformylation reactor.

d) Distillative separation

The organic reaction discharge which is obtained after the hydroformylation step and the decobalization does not contain converted olefins, aldehydes, alcohols, formic acid esters and high boilers and Traces of cobalt compounds. This discharge becomes a material separation (Step d) fed, in which the low boilers, preferably the unreacted olefins are separated from the valuable products (aldehyde, alcohol, formates).

The separation of the olefins from the Hydroformylation products can be by distillation or steam distillation respectively.

The low boiler fraction (top fraction) contains the unreacted olefins by hydrogenation of olefins created paraffins, dissolved Water and possibly small amounts of valuable products. she will in the hydroformylation step of the next reaction step or optionally passed the last reaction stage.

In the separation by distillation the decarburized hydroformylation mixture has a water content in the column feed between 0.1 and 5 mass%, preferably between 0.3 and 2 mass%, d. H. the separation is done with this water content carried out.

If necessary, the damp decobtained hydroformylation mixture water added.

The bottom product of the separation, containing the hydroformylation products (aldehydes, alcohols, formates etc.) contains preferably 0.01 to 1% by mass of water, in particular 0.05 to 0.5 Mass%. If appropriate, water is added to the column at a suitable point fed.

The separation by distillation can different pressures, preferably be carried out at reduced pressures. If the material separation is carried out by steam distillation, apply to the preferred water content in the bottom product is the same Limits as for the separation by distillation, namely 0.01 to 1, in particular 0.05 to 0.5 mass%.

The column feed has the column separation and the fraction with the hydroformylation products (aldehydes, Alcohols, formates, water, etc.) have a pH value less than or equal to 7th

The low boiler fraction obtained (top fraction) can be one or two phases. Your organic phase contains the unreacted olefins, the paraffins formed by hydrogenation of olefins, dissolved water and possibly small amounts of valuable products. It is in the hydroformylation step next reaction stage or optionally the last reaction stage.

The after the separation of the unconverted Fractions containing olefins with the hydroformylation products any hydroformylation stage separated or hydrogenated together (step e).

e) hydrogenation

The after the separation of the unconverted Fractions containing olefins with the hydroformylation products any hydroformylation stage separated or hydrogenated together (step e).

It is optionally possible to use the decobtained hydroformylation mixture the last stage without hydrogenating the olefins, d. that is, step d is omitted in this process variant in the last stage.

You can z. B. nickel, Copper, copper / nickel, copper / chrome, copper / chrome / nickel, zinc / chrome, Nickel / molybdenum catalysts use. The catalysts can unsupported be, or the hydrogenation substances or their precursors can Carrier, such as silicon dioxide or aluminum dioxide his.

Preferred catalysts on which the hydroformylation mixtures are hydrogenated, in each case 0.3 to 15 mass% copper and nickel and 0.05 as activators up to 3.5 mass% chromium and advantageously 0.01 to 1.6 mass%, preferably 0.02 to 1.2 masses of an alkali component on a carrier material, preferably alumina and silica. The quantities refer to the not yet reduced catalyst. The alkali component is optional.

The catalysts become advantageous used in a form in which they have low flow resistance offer, e.g. B. in the form of granules, pellets or moldings, such as Tablets, cylinders, extrudates or rings. You will be expedient before activated their use, e.g. B. by heating in a hydrogen stream.

The hydrogenation, preferably a liquid phase hydrogenation, is generally carried out under a total pressure of 5 to 100 bar, in particular carried out between 15 and 500 bar. Hydrogenation in the gas phase can also be carried out at lower pressures, with correspondingly large ones Gas volumes. If several hydrogenation reactors are used, the total pressures in the individual reactors within the specified pressure limits be the same or different.

The reaction temperatures for hydrogenation in the liquid or gaseous phase are generally between 120 and 220 ° C., in particular between 140 and 180 ° C. Examples of such hydrogenations are in the patent applications DE 198 42 369 and DE 198 42 370 described.

In the process according to the invention, the hydrogenation is carried out in the presence of water. The water required can be contained in the reactor feed. However, it is also possible to feed water into the hydrogenation apparatus at a suitable point. In the case of gas phase hydrogenation, water is expediently supplied in the form of water vapor. A preferred hydrogenation process is liquid phase hydrogenation with the addition of water, as described, for example, in DE 100 62 448 is described.

The hydrogenation is preferred at a water content of 0.05 to 10 mass%, in particular 0.5 to 5 mass%, very particularly 1 to 2.5 mass% carried out. The Water content is determined at the hydrogenation discharge.

The following examples are intended to Explain invention, without restricting the scope of application resulting from the description and the claims results.

Example 1 (comparative example)

hydroformylation of di-n-butene in the absence of water

In a 21-high pressure autoclave, which was provided with a stirrer and electrical heating, 800 g of di-n-butene (C ₈ -olefin mixture from the octol process from OXENO GmbH) were in the presence of 2.35 g of di-cobalt octacarbonyl from Fa .Fluka hydroformylated at 180 ° C and a constant synthesis gas pressure of 280 bar. The synthesis gas contained 50 vol.% CO and 50 vol.% H ₂ . The di-n-butene loaded with cobalt carbonyls and containing about 0.1% by mass of cobalt (calculated as metal) was hydroformylated for 3 hours under the reaction conditions mentioned above. After cooling to room temperature, the reaction mixture was released from the autoclave in a pressure-relieved manner and freed from the cocatalyst by treatment with 5% acetic acid and air at 80.degree. 990 g of hydroformylation mixture were obtained, which were analyzed by gas chromatography. The results are shown in Table 1, Column 1. Thereafter, a di-n-butene conversion of 91.1% was achieved with a value product selectivity of 85.0%, corresponding to a value product yield of 77.4,% based on the di-n-butene used. C ₉ aldehydes, C ₉ alcohols and isononyl formates were considered as valuable products.

Example 2 (according to the invention)

Hydroformylation of Di-n-butene in the presence of water

In the same test device as in Example 1, 800 g of di-n-butene (C ₈ -olefin from the Octol process from OXENO GmbH) were hydroformylated in the presence of a cobalt catalyst and water at 180 ° C. and the synthesis gas pressure kept constant at 280 bar , The synthesis gas contained 50 vol.% CO and 50 vol.% H ₂ . For the preparation of the active cobalt catalyst, an aqueous cobalt acetate solution with 1.35 mass% Co was used as the catalyst precursor. This cobalt acetate solution was treated with synthesis gas for 7 hours at 170 ° C. and 280 bar. After cooling to room temperature and relaxing, the cobalt carbonyls formed were converted into the organic phase by extraction with starting material di-n-butene. After the aqueous phase had been separated off, the di-n-butene loaded with cobalt carbonyls had a content of 0.09% by weight of cobalt (calculated as metal) and 1.5 masses. % Water hydroformylated for 3 hours under the above reaction conditions.

After cooling to room temperature, the reaction mixture was released from the autoclave in a pressure-relieved manner and freed from the cocatalyst by treatment with 5% acetic acid and air at 80.degree. 995 g of hydroformylation mixture were obtained, which were analyzed by gas chromatography. The results are shown in Table 1, Column 2. Thereafter, a di-n-butene conversion of 91.5% was achieved with a product selectivity of 89.8%, corresponding to a product yield of 82.2% based on the di-n-butene used. C ₉ aldehydes, C ₉ alcohols and isononyl formates were considered as valuable products.

Compared to hydroformylation without Water in the reaction mixture according to Example 1 leads to the hydroformylation Presence of water to increase the product yields around 5% percentage points.

Table 1 Composition of hydroformylation mixtures

Example 3 (comparative example):

C ₉ aldehyde hydrogenation in the liquid phase / crude aldehyde - water-free educt

One liter of a reaction discharge from the co-catalyzed hydroformylation of dibutene with 1.20% by weight of water and 5.46% by weight of high boilers was removed after removing the water (except for 150 ppm of residual water) by laboratory distillation in a circulation apparatus at 180 ° C and 25 bar absolutely hydrogenated on 100 g of a Cu / Cr / Ni catalyst on Al ₂ O _{3 support} in the liquid phase. The amount of exhaust gas was 1 Nl / h. The educt and product analyzes are shown in Table 2.

Table 2:

How to take from Table 2 can, the high boilers in the hydrogenation of isononanal without Do not split water additive.

Example 4 (according to the invention):

C ₉ aldehyde hydrogenation / crude aldehyde - water-containing educt

One liter of a reaction discharge from the co-catalyzed hydroformylation of dibutene with 1.20% by weight of residual water and 5.46% by weight of high boilers was dissolved in 100 g of a Cu / Cr / Ni in a circulating apparatus at 180 ° C. and 25 bar -Catalyst on Al ₂ O ₃ carrier hydrogenated in the liquid phase. The amount of exhaust gas was 1 Nl / h. The educt and product analyzes are shown in Table 3, calculated anhydrous.

Table 3:

As can be seen in Table 4, are used in the hydrogenation of crude isononanal in the presence of water in the educt the high boilers are partly split into valuable products and the formats are broken down more quickly and practically quantitatively. To the hydrogenation contained the liquid Reactor discharge 1.01 wt .-% water.

Claims (11)

Process for the preparation of aliphatic alcohols with 7-17 carbon atoms by one or more reaction stages, each comprising the steps a) cobalt-catalyzed hydroformylation of olefins with 6 to 16 carbon atoms, b) oxidative decomposition of the active cobalt catalyst in the hydroformylation output by reaction with oxygen-containing Gases c) separation of the mixture from b) into an aqueous phase containing cobalt salt and an organic phase containing the aliphatic aldehydes, d) separation of the organic phase by distillation into a low boiler fraction containing unreacted olefins and an aldehyde-containing bottom fraction. e) hydrogenation of the aldehyde-containing bottom fraction, characterized in that all process steps are carried out in the presence of water. A method according to claim 1, characterized in that the cobalt-catalyzed hydroformylation (step a) with a water content the liquid Phase from 0.1-10 Mass% performed becomes. Method according to one of claims 1 to 2, characterized in that that the separation of the unreacted olefins in step d) done by steam distillation. Method according to one of claims 1 to 3, characterized in that that the bottom fraction containing aldehyde obtained in step d) has a Has water content of 0.01 to 1 mass%. Method according to one of claims 1 to 4, characterized in that that the hydrogenation of the aldehyde-containing bottom fraction in step e) is carried out with a water content of 0.05 to 10 mass%. Method according to one of claims 1 to 4, characterized in that that the pH of the water is lower in stages a, b, c and d or is equal to 7. Method according to one of claims 1 to 6, characterized in that that the low boiler fraction separated off in step d) completely or partially returned in step a). Method according to one of claims 1 to 6, characterized in that that at least two reaction stages are run through, the separated in step c) low boiler fraction in step a) the following reaction stage. Method according to one of claims 1 to 6, characterized in that that at least two reaction stages are run through, the separated in step d) low boiler fraction in step a) the following reaction stage, and that in the steps d) all reaction stages separated aldehyde-containing bottom fractions are hydrogenated in a common step e). Method according to one of claims 1 to 6, characterized in that that two reaction stages are followed, the one in step d) the first boiling stage separated low boilers in step a) the second reaction stage and the aldehyde-containing bottom fraction of steps d) of both stages in step e) of the first reaction stage be directed. Method according to one of claims 1 to 6, characterized in that that two reaction stages are followed, the one in step d) the first boiling stage separated low boilers in step a) the second reaction stage and steps b), c) and e) for both reaction stages are carried out together.