DE10035120A1 - Hydroformylation of olefins is carried out in two steps R1 and R2 in a reactor system, whereby the olefin containing feed, carbon monoxide, hydrogen and the discharge from R1 is fed to R2 - Google Patents

Abstract

A process for the hydroformylation of olefins by the reaction of carbon monoxide and hydrogen in the presence of a hydroformylation catalyst in carried out in two steps (R1) and (R2) in a reactor system, whereby the olefin containing feed, carbon monoxide, hydrogen and the discharge from R1 is fed to reaction step R2 and partially reacted, catalytically and the output from (R1) is fed to (R2). A process for the hydroformylation of olefins by the reaction of carbon monoxide and hydrogen in the presence of a hydroformylation catalyst in carried out in two steps (R1) and (R2) in a reactor system, whereby -the olefin containing feed, carbon monoxide, hydrogen and the discharge from R1 is fed to reaction step R2 and partially reacted, catalytically -the discharge from (R2) is separated to form a catalyst containing liquid fraction (F1), a product containing fraction (F2) and an unreacted olefin containing fraction (F3) -at least some of the fraction (F3), optionally with at least some of the fraction (F1) as well as carbon monoxide and/or hydrogen are fed to reaction step (R1) and catalytically reacted -the output from (R1) is fed to (R2)

Description

The present invention relates to a method for hydroformy olefins by reaction with carbon monoxide and what serstoff in the presence of a hydroformylation catalyst in egg a reaction system that comprises two reaction stages.

The hydroformylation or oxo synthesis is an important big one technical process and is used for the production of aldehydes Olefins, carbon monoxide and hydrogen. These aldehydes can if necessary in the same work step or successively in one separate hydrogenation step with hydrogen to the corresponding Alcohols are hydrogenated. The reaction itself is highly exothermic and generally runs under increased pressure and at elevated Temperatures in the presence of transition metal catalysts. Compounds or are generally used as catalysts Complexes of subgroup VIII metals, especially Co, Rh, Ir, Pd, Pt or Ru compounds or complexes used, the unmodified or e.g. B. with amine or phosphine-containing verbin can be modified.

A generally important goal of industrial processes and hence hydroformylation is the necessary reactor minimize volume in order to increase investment and operating costs reduce. However, the technical effort should be as possible who does not or not significantly increases the product processing the.

It is known to use reactors in the form of a cascade for a given reaction space a higher turnover than in one To achieve a single reactor of the same volume. It can in space mean both reactors with the same as with different ones. Mixing characteristics can be cascaded. An overview be regarding reactors and reaction technology optimization z. B. in Baerns et al., Chemical Reaction Engineering, Georg- Thieme-Verlag, Stuttgart, New York, 1987, Chapter 10, pp. 372-415. Furthermore, several, already cascaded or different switched reactors as a component in a reactor cascade be set. A characteristic feature of a conventional reactor cascades is that the educt input concentration in (n + 1). Reak the cascade is lower than the educt input concentration in the nth reactor of the cascade. Will the reactors be such Cascade under the same reaction conditions as temperature, pressure  and residence time operated, for a reaction order <O for olefin, the specific product performance, i. H. at for example in a hydroformylation, the converted olefin amount per unit of time and volume of the reaction space, im (n + 1). Reactor is lower than in the nth reactor. Thus, the in the reaction space available to the reactor cascade is not ef fectively used.

In many cases, technically accessible olefins are used for hydroformylation mixtures, e.g. B. from the processing of petroleum by Steamcrac ken, the Shell Higher Olefin Process (SHOP), the Ziegler-Syn these, Fischer-Tropsch synthesis, paraffin dehydration, wax crack ken, chlorination / dehydrochlorination, etc., used. These oils fine can z. B. mixtures of isomers with different reactants vity against hydroformylation included. These include on the one hand oligomers of lower olefins, such as propene, butenes, Pentenes, hexenes etc. This also includes isomeric olefin mixtures, which are produced by oligomerization of propenes, butenes etc. can be, such as di-, tri- and tetrapropene and butene. Oligomes Risks of n-butenes are e.g. B. after the Octol® process from Hüls and the Dimersol® process from IFP. Are such olefin mixtures, the z. B. olefins with an under different number of carbon atoms and / or different Contain isomers of an olefin with different reactivity ten, a hydroformylation in a conventional reactor cascade trained, preferably the easily hydroformylatable Olefins in the first reactor or in the first reactors of the Kas kade hydroformylated, while the heavier hydroformylatable Olefins accumulate in the reaction discharge from the front reactors chern. Are the downstream reactors of the cascade at im Operated essentially the same reaction conditions as that most reactor, the olefin conversion either remains incomplete or it is used to achieve a substantially complete one Sales a high total reaction space needed. Both lead to economic disadvantages, because on the one hand the costs for the olefin mixtures used an essential factor of the application material costs of the hydroformylation process, on the other hand an increased reactor volume, as previously stated, with higher ones Investment or operating costs is connected.

If the pro product-containing reaction discharge from the first reactor by several further reactors are performed and / or the downstream ones Reactors under more severe reaction conditions, e.g. B. higher Pressure and / or higher temperatures than the first Re actuator, there are often undesirable side reactions of the already formed hydroformylation products, such as. B. Aldol  condensation, acetal formation, table pocket reactions etc. This on the one hand often has the formation of high-boiling by-products Follow and generally leads to a reduction in off prey.

The high-boiling by-products accumulate on thermal waste separation of the catalyst from the hydroformylation products in the Bottom of the distillation and must be technically complex Measures are removed from the catalyst-containing return flow the. Without this distance, the concentration of the acti ven catalyst reduce or the amount of the required reco led increase catalyst flow.

GB-A-1 387 657 describes a hydroformylation process wherein the olefin used tei in a first reaction zone is reacted, products and unreacted olefin as gas electricity are discharged, the products separated and that unreacted olefin partially returned to the first reactor leads and partly again in a second reaction zone Hydroformylation is subjected. A return not reversed set products from the second reaction zone is omitted.

US 3,518,319 describes a process for the production of un branched alcohols in a two-stage reactor cascade, the entire discharge of the first reactor into the second reactor is fed and part of the discharge from the second reactor isolated aldehyde is returned to the first reactor.

US 3,868,422 describes a hydroformylation process in a reactor cascade, in which the synthesis gas in countercurrent ge leads.

EP-A-0 805 138 describes a process for hydroformylation in two reaction stages, the olefin-containing exhaust gas being the first Reaction stage in a second reaction stage at higher pressures ken than is implemented in the first stage.

US 4,593,127 describes a two-stage hydroformylation process in which each stage can comprise several reactors and in each of the two stages a gas or liquid flow re is cyclized. A recycling of unreacted olefin or recovered catalyst from the second to the first stage does not happen.

WO-A 94/29018 describes a hydroformylation process in a tubular reactor cascade in which synthesis gas and / or olefin not only in the first but also in the second reactor  can be fed. A return of unconverted Olefin from the second or a subsequent reactor in the the first reactor does not take place.

DE-A-44 08 950 and EP-A-0 695 734 describe hydroformy lation process, which includes a precarbonylation stage, a hydro formylation stage and two extraction stages include. there becomes a rhodium catalyst homogeneously dissolved in the reaction medium used for recovery from the hydroformylation discharge with an aqueous solution of a complexing agent extra hiert and then fed to the precarbonylation stage becomes. A return of unreacted olefin to the previous carbonylation stage is not described.

The present invention has for its object a hydro to provide the formylation process that the Reacti ons space of a reaction system as effectively as possible, d. H. good olefin conversion with the smallest possible reactor total volume allowed.

Surprisingly, it has now been found that this object is achieved by a hydroformylation process in which the olefin to be hydroformylated is fed into the second reaction stage of a reaction system and hydroformylated to a partial conversion, the discharge from this reaction stage is separated and the unreacted olefin is separated into the feeds the first reaction stage of the reaction system, catalytically hydroformylates there again and feeds the discharge from reaction stage R ₁ into reaction stage R ₂ .

The present invention therefore relates to a process for the hydroformylation of olefins by reaction with carbon monoxide and hydrogen in the presence of a hydroformylation catalyst in a reaction system which comprises two reaction stages R ₁ and R ₂ , which is characterized in that

• - feeding into the reaction stage R ₂ is an olefin-comprising feed, carbon monoxide, hydrogen, and the effluent from the stage R ₁ and partially catalytically reacted,
• separates the discharge from the reaction stage R ₂ in a separation stage into a catalyst-containing liquid fraction F1, a product-containing fraction F2 and an unreacted olefin-containing fraction F3,
• partly or completely feeds the fraction F3 and optionally partly or completely the fraction F1 and carbon monoxide and / or hydrogen into the reaction step R ₁ and converts it,
• - Feeds the discharge from reaction step R ₁ into reaction step R ₂ .

The reaction system used according to the invention has two reaction stages R ₁ and R ₂ , each of which can comprise one or more, the same or different reactors. Both the reactors of each individual stage and the reactors forming the various stages of the cascade can each have the same or different mixing characteristics. The individual reactors of the two stages can, if desired, be divided one or more times by internals. If two or more reactors form a single stage of the reaction system, they can be interconnected as desired, e.g. B. pa parallel or in series. Suitable reactor circuits of each stage are e.g. B. in Dialer, Leo, monograph from Winnacker, Küchler, Chemical Technology, Volume 7, 3rd edition 1975, Chapter 4, be written. In the simplest case, a reaction stage is formed by a single reactor.

Suitable, if necessary pressure-resistant reaction apparatus for the Hydroformylation are known to the person skilled in the art. These include all Common reactors for gas / liquid reactions, such as. B. Tubular reactors, stirred tanks, gas circulation reactors, bubble columns etc., which can be subdivided if necessary by internals nen.

According to the invention, the hydroformylation is fed the olefin in the second stage of the reaction system, d. H. the the reactor used to feed the olefin is always at least least a hydroformylation reactor upstream, the discharge also in the reactor used for the olefin feed is fed.

The composition of the synthesis gas from carbon monoxide and hydrogen used in the process according to the invention can vary in wide ranges. If desired, the same or different molar ratios of CO to H _{2 can be} set in the cascade reactors used for hydroformylation. The molar ratio of carbon monoxide and hydrogen is usually about 1:15 to 15: 1, preferably 10: 1 to 1:10, in particular special 2: 1 to 1: 2.

The temperature in the hydroformylation reaction in reaction stages R ₁ and R ₂ is generally in a range from about 20 to 200 ° C., preferably about 50 to 190 ° C., in particular about 90 to 190 ° C. If desired, a higher temperature than in the second reaction stage can be set in the first reaction stage, e.g. B. to achieve the most complete possible conversion of possibly more difficult hydroformylatable olefins. If a reaction stage comprises more than one reactor, these can also have the same or different temperatures. The reaction in the reaction stages R ₁ and R _{2 is} preferably carried out at a pressure in a range from about 1 to 700 bar, preferably 1 to 600 bar, in particular 1 to 400 bar. The reaction pressure can be varied in the reactors used for the hydroformylation, depending on the activity of the hydroformylation catalyst used. For example, the hydroformylation catalysts described in more detail below allow a reaction in a range of low pressures, such as in the range from 1 to 100 bar.

The reactor volume and / or the residence time of reaction stage R ₂ are selected such that in general at least about half of the freshly fed-in olefin is reacted. In general, the conversion in reaction stage R ₂ based on the amount of olefin in the olefin-containing feed is thus at least 50% by weight, preferably at least 60% by weight.

The total amount of olefin in the reaction stage R _{2 used} for the olefin feed is composed of the amount of freshly fed in olefin and the amount of olefin fed in with the reaction discharge from the upstream reaction stage R ₁ . The reaction stage R ₂ thus has a high olefin inflow, so that a high specific product performance (amount of olefin converted per unit of time and volume) can be achieved in this stage.

The discharge from the reaction stage R ₂ is fed to a separation stage for the recovery of a catalyst-containing liquid fraction F1, a product-containing fraction F2 and an unreacted olefin-containing fraction F3. In addition to the fractions F1 to F3, at least one further fraction can optionally be separated off. B. may contain synthesis gas-containing exhaust gases, inerts etc. and mixtures thereof. Suitable devices for forming the separation stage are the usual apparatuses known to the person skilled in the art. These include e.g. B. separator for the separation of gaseous and / or volatile substances from liquid, separation devices for separating volatile compounds, such as distillation columns, for. B. tray columns, which can optionally be equipped with bells, sieve plates, sieve trays, valves, etc., spray columns, which can be equipped with rotating structures if desired, for. B. rotary column columns, Füllkör persäulen with bulk fillings or column internals, Rieselko columns, evaporators, such as thin-film evaporators, falling film evaporators fer, wiper blade evaporators, Sambay evaporators etc. and combinations thereof. This also includes devices for the separation of immiscible liquid phases, such as decanters and phase separation vessels.

According to a suitable embodiment, the discharge of the reaction stage R _{2 is} first subjected to a gas-liquid separation in a separator. The gas stream obtained in this way generally contains unreacted carbon monoxide and hydrogen and, if appropriate, additional inert gases such as nitrogen and / or saturated, volatile hydrocarbons which are not accessible to hydroformylation, such as, for. B. methane, and possibly small proportions of entrained starting materials and / or products.

The gaseous products can, if appropriate after further separation and / or after the addition of carbon monoxide and / or hydrogen, be wholly or partly recycled into one of the two hydroformation reaction stages R ₁ or R ₂ , or both. If desired, the gaseous products can also be discharged in whole or in part.

The reaction obtained after separation of the gaseous products Discharge can be carried out in one of the aforementioned devices or in an egg A combination of several of these devices in the fractions F1 to F3 can be separated. One to carry out these doors Suitable combination of equipment includes z. B. mind least a phase separation device or an evaporator and / or at least one distillation column.

The separation stage is preferably designed so that the thermi cal load on the hydroformylation products as low as possible is to undesirable side reactions and especially education to avoid high-boiling by-products. Generally the liquid fraction F1 containing catalyst after separation by phase separation or as a residue (bottom) of an evaporation and / or a distillation. The catalyst-containing liquid fraction F1 contains u. U. inert solvents, such as ali phatic and aromatic hydrocarbons, alcohols etc. The Fraction F1 can also contain high-boiling by-products as a solvent tel included. If necessary, fraction F1 can also be one smaller proportion of non-separated hydroformylation product included.  

The separation into the product-containing fraction F2 and not reacted olefin-containing fraction F3 is preferred by fractional distillation using at least one of the aforementioned separation devices. A Auf is also suitable separation by another of the separation processes mentioned above, e.g. B. by extraction.

When fraction F2 and F3 are separated, one is possible good separation performance with the lowest possible thermal load the aldehydes and / or alcohol formed in the hydroformylation get aimed. There is a small proportion of hydroformyly tion products in the olefin-containing fraction F3, which in the Hy droformylation process, generally uncri table. Preferably contains the one obtained in the separation product-containing fraction F2 at most 5% by weight, preferably at most at least 1% by weight of unreacted olefin. If necessary, the Fraction F2 also contains saturated hydrocarbons contain the z. B. at u. U. as a side reaction of the Hydro Formation occurring olefin hydrogenation can arise. Before the olefin-containing fraction F3 preferably contains at most 20 wt .-%, preferably at most 5 wt .-% Hydroformylierungspro products. In this way, the separation stage can be easily and cheaply design so that the thermal load on the hydroformy lation products is kept low, without large amounts of olefins to lose.

The catalyst-containing liquid fraction F1 can before its return Leadership in the hydroformylation process one or more work steps are subjected. The is preferably Proportion of hydroformylation products, i.e. H. Aldehydes and / or Alcohols, in the recycled fraction F1 0 to 30 wt .-%, ins particularly 0 to 20% by weight. Because a higher proportion of aldehydes and / or alcohols in the recycled fraction F1 under certain circumstances the increased formation of high-boiling by-products can lead the fraction F1 before it is fed into the Reaction step R1, if desired, a cleaning step for Ab separation of the hydroformylation products, such as. B. a still lation.

Fraction F1 can continue to a cleaning step wise or complete removal of high-boiling by-products be subjected. This can be done both with and independently of the separation of hydroformylation product described above ten. For this purpose, e.g. B. a part or the full permanent fraction F1 discontinuously or continuously the hydroformylation process removed and worked up become. Preference is given to avoid enrichment of  High boilers in the catalyst circuit each a partial flow of Fraction F1 discharged discontinuously or continuously and worked up. A suitable method for cleaning the Fraction F1 is e.g. B. membrane filtration. The mem bran material and / or the hydroformylation catalyst used tor or the combination of catalyst and kokata used Analyzer selected so that either the catalyst component or the high-boiling component preferably permeates the membrane, so that a catalyst-rich and a catalyst-poor fraction re results. The catalyst-rich fraction F1 can then in the Hy droformylation process.

Another suitable method for cleaning the catalyst containing fraction F1 is the isolation of the catalyst, e.g. B. by precipitation of a catalyst / cocatalyst complex, e.g. B. by changing the polarity of the catalyst-containing fraction F1 by adding a suitable solvent. The precipitated Ka Talysator can be separated and given by conventional methods if after further purification in the hydroformylation process be returned.

Another suitable method for cleaning the catalyst Fraction F1 contains the injection of water vapor for the partial or complete removal of the high-boiling By-products. This steam treatment can, if necessary with a separation of the high boilers in a distillation unit lonne or an evaporator can be combined.

The catalyst-containing fraction F1 is, optionally after egg Processing as described above, partially or completely dig fed into reaction stage R1 of the cascade and thus into recycled the hydroformylation process. If the first reak tion stage comprises more than one reactor, the fraction F1 both completely in the first reactor of this stage as well partly in the first reactor and partly in another reak tion of this level.

1 to 100% by weight, particularly preferably 10 to 100% by weight, in particular 20 to 99% by weight, of the catalyst-containing fraction F1 are preferably fed into the reaction stage R ₁ .

According to a suitable embodiment, the catalyst-containing fraction F1 is only partially fed into the reaction stage R ₁ . Under certain circumstances, undesired catalyst accumulation in the first reaction stage can be avoided.

The product-containing fraction F2 can, if desired, a white teren processing or further processing according to known methods, such as the hydrogenation of the aldehydes to alcohols, the oxidation to car bonic acids, aldol condensation, etc.

Fraction F3 obtained after separation of the discharge from reaction stage R ₂ in the separation stage contains the major proportion of the olefins which were not reacted in reaction stage R ₂ . By feeding fraction F3 into the first reaction stage, these olefins run through the complete reactor cascade, including reaction stage R ₂ used to feed the fresh olefin. This is particularly advantageous if an olefin mixture which comprises at least one lighter and at least one heavier hydroformylatable olefin is used for hydroformylation. The more hydroformylatable olefins can be hydroformylated in reaction stage R ₂ under sufficiently mild conditions and their oxo products can then be isolated in the separation stage. Since they do not go through the entire cascade, as is the case with hydroformylation processes customary in the prior art, side reactions of the hydroformylation products formed, such as, for. B. aldol condensation and Tischtschenkoreak tion avoided. The more difficult to hydroformylate olefins can be subjected to hydroformylation again in the first stage of the cascade under possibly more drastic reaction conditions than in the second stage of the cascade.

The fraction F3 obtained after the separation of the discharge from the reaction stage R ₂ in the separation stage may optionally have further compounds in addition to the unreacted olefins, which, if desired, can be separated off before feeding into the reaction stage R ₁ . These include e.g. B. un under the reaction conditions inert components, such as paraffins, which are obtained as by-products of the hydroformylation by hydrogenating a portion of the olefins. If the separation of these components has not already taken place in a gas separator of the separation stage or if this separation was incomplete, fraction F3 can either be removed from the hydroformylation process in part or be subjected to a work-up before it is fed into reaction stage R ₁ . The fraction F3 removed is generally about 0 to 70% by weight, before 0 to 50% by weight, in particular 0 to 20% by weight, of the fraction F3 which has left the separation stage.

Suitable processes for the separation of inert substances, such as paraffins, are z. B. distillation processes and membrane separation processes. Ge if desired, the paraffins which have been separated off can be removed by suitable Methods such as B. chlorination / dehydrochlorination, catalytic  Dehydration etc., converted to olefins and again in the hydro formylation process can be fed.

The weight ratio of the fraction F3 fed into the reaction stage R ₁ to the fed fraction F1 is preferably in a range from about 10: 1 to 1:10, in particular 5: 1 to 1: 5.

The reaction conditions, such as. B. the dwell time, the tempera ture and pressure, can be used in the individual stages and reactors the cascade may be the same or different.

The hydroformylation conditions in the first reaction stage of the cascade are preferably more drastic than in the reaction stage R ₂ used to feed the olefin. In general, one or more of the parameters selected from the catalyst concentration, residence time, temperature and pressure then have higher values than the corresponding parameter (s) in reaction stage R ₂ . The required values depend on the olefin to be hydroformylated and the chosen catalyst. They can be determined easily by a specialist.

If at least one of the two stages R ₁ and / or R _{2 of} the reactor cascade has more than one reactor, the reaction conditions in the reactors of the stage can be the same or different. Here, for. B. a single, several or all of the above-mentioned reaction parameters form a gradient from the value of the first reactor to the value of the xth reactor of a stage.

Preferably, the ratio of mass of the hydroformylation catalyst per mass of reactor charge from reaction stage R ₂ to reaction stage R ₁ , ie the quotient

in a range from about 1: 1 to 1:10.

The residence time in reaction stage R ₁ is preferably 1 to 10 times, in particular 1 to 5 times, the residence time in reaction stage R ₂ .

The temperature in reaction stage R ₁ is preferably the same as or higher than the temperature in reaction stage R ₂ . In particular, the temperature in reaction stage R ₁ is 10 to 100 ° C higher than in reaction stage R ₂ .

The pressure in reaction stage R ₁ is preferably the same as or higher than the pressure in reaction stage R ₂ . In particular, the pressure in reaction stage R ₁ is 5 to 300 bar higher than the pressure in reaction stage R ₂ .

According to a preferred embodiment in the fiction hydroformylation process a two-stage reactor cascade used.

An advantageous embodiment of the method according to the invention is shown in FIG. 1 and is explained below. Fig. 1 shows a schematic representation of the process according to the invention using two reactors. Plant details that are self-evident and are not required to illustrate the method according to the invention were not included in the figure for reasons of clarity. The embodiment of the process according to the invention shown in the figure comprises a two-stage hydroformylation and a separation stage comprising a gas separator and a distillation column. Instead of these devices of the separation stage can also be used on other of the aforementioned devices.

According to FIG. 1, an olefin-containing feed containing the olefin or olefins to be hydroformylated, as well as carbon monoxide, hydrogen and the discharge from the reactor 1 are fed into the reactor 2 and hydroformed there up to a partial conversion. The discharge from the reactor 2 is passed into a separation stage comprising a gas separator 3 and a distillation column 4 . The gas stream separated in the gas separator 3 , which essentially has unconverted carbon monoxide and / or hydrogen and, if appropriate, inert gases and saturated hydrocarbons, can, if appropriate after separation of the inert gases and / or saturated hydrocarbons (not shown), be wholly or partly returned to the reaction or be removed. The liquid discharge from the gas separator 3 is separated in the distillation column 4 into a catalyst-containing liquid fraction F1, a product-containing fraction F2 and an unreacted olefin and fraction F3 containing any inert. The catalyst-containing fraction F1 is fed into the reactor 1 and, if appropriate, partly into the reactor 2 , if appropriate after removal and removal of part of the high-boiling by-products contained. The product-containing fraction F2 is removed from the hydroformylation process, if necessary for immediate further processing. The non-converted olefin-containing fraction F3 is fed into the reactor 1 , if appropriate after separation and work-up (not shown) or the removal of part of the nonhydroformylatable compounds present. The discharge from reactor 1 is fed entirely into reactor 2 . In the same way, the reactors can first be filled with a catalyst.

As substrates for the hydroformylation process according to the invention In principle, all connections are considered, which one or contain several ethylenically unsaturated double bonds. These include e.g. B. olefins selected from α-olefins, internal straight chain and branched olefins (olefins, at which the double bond is not in the α position), Cy cloolefins, functionalized olefins, di- and polyenes and Mixtures of these. These are preferably olefins with 2 to 20 carbon atoms.

Suitable α-olefins are e.g. B. ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonen, 1-decene, 1-undecene, 1-dodecene etc.

Suitable straight-chain internal olefins are preferably C ₄ -C ₂₀ -olefins, such as 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, 3-heptene, 2-octene, 3-octene, 4- Octene etc.

Suitable branched, internal olefins are preferably C ₄ -C ₂₀ -olefins, such as isobutene, 2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene, branched, internal heptene mixtures, branched, internal octene mixtures, branched, internal non-mixtures, branched, internal decene mixtures, branched, internal undecene mixtures, branched, internal dodecene mixtures etc.

Suitable olefins to be hydroformylated are furthermore C ₅ - to C ₈ -cycloalkenes, such as cyclopentene, cyclohexene, cycloheptene, cyclooctene and their derivatives, such as, for. B. whose C ₁ - to C ₂₀ alkyl derivatives with 1 to 5 alkyl substituents. Suitable olefins to be hydroformylated are furthermore vinyl aromatics, such as styrene, α-methylstyrene, 4-isobutylstyrene etc. Suitable olefins to be hydroformylated are furthermore α, β-ethylenically unsaturated mono- and / or dicarboxylic acids, their esters, half-esters and amides, such as acrylic acid, methacrylic acid acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, methyl 3-pentenoate, methyl 4-pentenoate, methyl oleate, methyl acrylate, methyl methacrylate, unsaturated nitriles such as 3-pentenenitrile, 4-pentenenitrile, acrylonitrile, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl, etc., C ₁ to C ₂₀ -alkenols, -alkenediols and -alkadienols, such as 2,7-octadienol-1. Suitable substrates are further di- or polyenes with isolated or conjugated double bonds. These include e.g. B. 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, vinylcyclohexene, dicyclopentadiene, 1,5,9-cyclooctatriene etc.

Suitable substrates for the hydroformylation process according to the invention are also olefin mixtures, preference being given to using technically accessible mixtures. These include e.g. B. the Ziegler olefins obtained by targeted ethene oligomerization in the presence of alkyl aluminum catalysts. These are essentially unbranched olefins with a terminal double bond and an even number of carbon atoms. These also include the olefins obtained by ethene oligomerization in the presence of various catalyst systems, e.g. B. the obtained in the presence of Al aluminum alkyl chloride / titanium tetrachloride catalysts, predominantly linear α-olefins and the α-olefins obtained in the presence of nickel-phosphine complex catalysts according to the Shell Higher Olefin Process (SHOP). Suitable technically accessible olefin mixtures are still used in the paraffin dehydrogenation of corresponding petroleum fractions, e.g. B. the so-called petroleum or diesel oil fractions obtained. Essentially three processes are used to convert paraffins, primarily n-paraffins to olefins:

• - thermal cracking (steam cracking),
• - catalytic dehydration and
• - chemical dehydration through chlorination and dehydrochloria ren.

Thermal cracking mainly leads to α-olefins, while the other variants give olefin mixtures which exist in space also have olefins with an internal double bond. Suitable olefin mixtures are also those in metathesis or Telomerization reactions obtained olefins. These include e.g. B. the olefins from the Philipps triolefin process, a modified SHOP process from ethylene oligomerization, double bond Isomerization and subsequent metathesis (ethenolysis). Procedure Ren for the production of suitable olefins are still the Her production of neohexene by ethenolysis of di-i-butene, the Her position of α, ω-diolefins by ring-opening ethenolysis of Cy cloolefins, the metathesis polymerization of cycloolefins to Po lyalkenamers followed by ethenolysis etc. General obtained a high n-α-olefin concentration in the ethenolysis.

Suitable in the hydroformylation process according to the invention usable technical olefin mixtures are still selected among dibutenes, tributes, tetrabutenes, dipropenes, tripropes  nen, tetrapropenes, mixtures of butene isomers, in particular Raffinate II, dihexenes, dimers and oligomers from the Dimersol® IFP process, Hüls Octolprocess®, polygas process etc.

Preferably, in the hydroformylation process according to the invention, an olefin mixture is used which comprises at least one lighter and at least one heavier hydroformylatable olefin. These include e.g. B. olefin mixtures, the components of which are selected from olefin isomers with the same number of carbon atoms and olefin mixtures from olefins of different carbon atoms, as described, for. B. can be obtained in the aforementioned technical processes for olefin production. Are suitable for. B. mixtures that contain n- and i-butenes and mixtures containing n-octene, isomeric methylheptenes and isomeric dimethylhexenes. These include e.g. B. the octene isomers from butene oligomerization. Also suitable are non-isomers which, for. B. from the propene oligomerization are available and dodecene isomers, the z. B. are available from Bu tenisomerization. Also suitable are mixtures of linear α-olefins containing z. B. 1-decene, 1-dodecene or 1-tetradecene, with linear internal olefins or with branched olefins, the z. B. are available by dimerization of short-chain olefins. Preferred vinylidene-branched olefins of the general formula R ¹ R ² C = CH ₂ , where R ¹ and R ² independently of one another are hydrogen and straight-chain and branched C ₁ - to C ₂₀ -alkyl radicals.

Suitable hydroformylation catalysts are the usual ones Transition metal compounds and complexes known to those skilled in the art can be used both with and without cocatalysts nen. The transition metal is preferably a Me tall of subgroup VIII of the periodic table and in particular around Co, Ru, Rh, Pd, Pt, Os or Ir, especially around Rh, Co, Ir or Ru.

In general, catalytically active species of the general formula H _x M _y (CO) _z L _{q are} formed from the catalysts or catalyst precursors used in each case under hydroformylation conditions, where M for the respective catalyst metal, L for modifying ligands which may be present and q, x , y, z stand for integers, depending on the valency and type of the metal as well as the binding strength of the ligand L. These include e.g. B. Rho dium catalysts that under the reaction conditions in rhodium carbonyl, so-called "bare rhodium" [RhH (CO) ₄ ], and cobalt catalysts, which can be converted under the reaction conditions into cobalt carbonyl [HCo (CO)] ₄ .

Suitable catalysts or catalyst precursors are in the Rule salts or complex compounds of the aforementioned Transition metals. Suitable salts are, for example Hydrides, halides, nitrates, sulfates, oxides, sulfides or the Salts with alkyl or aryl carboxylic acids or alkyl or Arylsulfonic acids. Suitable complex compounds are for example the carbonyl compounds of the metals mentioned as well as complexes whose ligands are selected from amines, Arylphosphines, alkylphosphines, arylalkylphosphines, olefins, Serve etc. and mixtures thereof. Are also suitable Catalyst systems made in situ from the above salts or Compounds and the ligands mentioned.

Particularly preferred rhodium catalysts or catalysts precursors are rhodium (II) and rhodium (III) salts such as Rhodium (III) chloride, rhodium (III) nitrate, rhodium (III) sulfate, Potassium rhodium sulfate (rhodium alum), rhodium (II) - or Rhodium (III) carboxylate, preferably rhodium (II) - and Rhodium (III) acetate, rhodium (III) ethylhexanoate, rhodium (III) oxide, Salts of rhodium (III) acid, trisammonium hexachlororhodate (III).

Also suitable are rhodium complexes of the general formula RhX _m L ¹ L ² (L ³ ) _n , in which
X for halide, preferably chloride or bromide, alkyl or aryl carboxylate, acetylacetonate, aryl or alkyl sulfonate, in particular phenyl sulfonate and toluenesulfonate, hydride or the diphenyltriazine anion,
L ¹ , L ² , L ³ independently of one another for CO, olefins, cycloolefins, preferably cyclooctadiene (COD), dibenzophosphole, benzonitrile, PR ₃ or R ₂ PA-PR ₂ , m for 1 or 3 and n for 0, 1 or 2 stand. R (the radicals R can be the same or different) is to be understood as meaning alkyl, cycloalkyl and aryl radicals, preferably phenyl, p-tolyl, m-tolyl, p-ethylphenyl, p-cumyl, pt-butylphenyl, pC ₁ -C ₄ -alkoxyphenyl, preferably p-anisyl, xylyl, mesityl, p-hydroxyphenyl, which may optionally also be ethoxylated, isopropyl, C ₁ -C ₄ -alkoxy, cyclopentyl or cyclohexyl. A stands for 1,2-ethylene or 1,3-propylene. L ¹ , L ² or L ³ are preferably independently of one another CO, COD, P (phenyl) ₃ , P (i-propyl) ₃ , P (anisyl) ₃ , P (OC ₂ H ₅ ) ₃ , P (cyclohexyl) ₃ , dibenzophosphole or benzonitrile.
X preferably represents hydride, chloride, bromide, acetate, tosylate, acetylacetonate or the diphenyltriazine anion, in particular hydride, chloride or acetate.

Suitable rhodium complexes are, for example, RhCl (PPh ₃ ) ₃ , RhCl (COO) (PPh ₃ ) ₂ , RhH (CO) (PPh ₃ ) ₃ and RhH (PPh ₃ ) ₄ . The rhodium carbonyl compounds such as tetrarhodium dodecacarbonyl or hexarhodium hexadecacarbonyl can also be used for the process according to the invention.

Ruthe nium salts or compounds are also suitable for the process according to the invention. Suitable ruthenium salts are, for example, ruthenium (III) chloride, ruthenium (III) acetate, ruthenium (IV) -, ruthenium (VI) - or ruthenim (VIII) oxide, alkali metal salts of ruthenium oxygen acids such as K ₂ RuO ₄ or KRuO ₄ or complex compounds of the general formula RuX ¹ X ² L ¹ L ² (L ³ ) _n , in which L ¹ , L ² , L ³ and n have the meanings given above and X ¹ , X ^{2 have} the meanings given for X (see above), for . B. RuHCl (CO) (PPh ₃ ) ₃ . The metal carbonyls of ruthenium such as trisruthenium dodecacarbonyl or hexaruthenium octadecacarbo nyl, or mixed forms in which CO is partly replaced by ligands of the formula PR ₃ , such as Ru (CO) ₃ (PPh ₃ ) ₂ , can be used in the process according to the invention.

Suitable cobalt compounds are, for example Cobalt (II) chloride, cobalt (II) sulfate, cobalt (II) nitrate, their Amine or hydrate complexes, cobalt carboxylates, such as cobalt acetate, Cobalt ethyl hexanoate, cobalt naphthanoate, and the Cobalt-caprolactamate complex. Here too they can Carbonyl complexes of cobalt such as dicobalt octacarbonyl, Tetracobalt dodecacarbonyl and hexacobalt hexadecacarbonyl be used.

The compounds of cobalt, rhodium and ruthenium mentioned are known in principle and sufficient in the literature wrote or you can from the specialist analog to the already known compounds are made.

Suitable palladium compounds are, for example, palladium hydride, palladium chloride, palladium iodide, palladium nitrate, palladium cyanide, palladium acetate, palladium sulfate, palladium oxide, (C ₆ H ₅ CN) ₂ PdCl ₂ , Na ₂ PdCl ₄ , Li ₂ PdCl ₄ etc. Suitable platinum compounds are, for example, platinum (IV) -Compounds, such as the salts of hexachloroplatinic acid with alkali metals or ammonium ions, platinum (IV) oxide or salts of platinum (IV) acid. Platinum (II) iodide and the complexes obtained therefrom by reaction with olefins, such as, for example, the alkali metal salts of trichloromonoethylene platinum, are also suitable. When using platinum catalysts, the presence of a tin (II) salt such as tin (II) chloride is recommended.

Compounds or complexes are preferred as catalysts of these transition metals used for activity and / or Influencing selectivity with nitrogen or phosphorus Ligands can be modified.

Suitable hydroformylation catalysts are e.g. B. in Beller et al., Journal of Molecular Catalysis A, 104 (1995), pp. 17-85, described, to which reference is made in full here. Suitable hydroformylation catalysts are also those in DE-A-196 21 967 catalysts described as ligands open chain or cyclic phosphorus compounds, preferably cyclic phosphaalkenes and phosphate aromatics, such as phosphabenzene, exhibit. This document is hereby fully described pulled.

Preferably, at least one, two or or multidentate ligand used. Preferred are ligands which at least one trivalent element of the fifth main group of the perio densystems, preferably nitrogen or phosphorus. These include the usual one-, two- and multidentate phosphite, phosphonite, phosphinite and phosphinli found how they z. B. Beller et al., Journal of Molecular Ca talysis A, 104 (1995), pp. 17-85, and in WO-A 95/30680 (Phos phine) and US-A-5,312,996 (phosphites).

These also include catalysts in which at least one monodentate or multidentate, aliphatic or aromatic amine or a polyamine is used as a cocatalyst. These amines or If desired, polyamines can be mixed with higher carboxylic acids derivatized, alkoxylated, alkylated or otherwise be modified. Those in the German are preferred Patent application P 198 01 437.2 described polyethyleneimines used in which at least some of the imine nitrogen by alkyl, cycloalkyl, aryl, arylalkyl and / or Alkylcarbonyl radicals with up to 30 carbon atoms or Hydroxy (poly) oxyalkylene residues with up to 500 alkylene oxide units are substituted.

Preferably, a com plex compound used as a hydroformylation catalyst, from the distillative separation of the hydroformylation carry essentially no ligand into the De in the separation step breastfeeding phase passes d. H. the vapor pressure of the ligands is in  Generally much lower than the vapor pressure of the Hydrofor methylation products.

If desired, the process according to the invention can be carried out using or be carried out without the addition of a solvent. As Lö can preferably be part of the hydroformyl aldehydes and their higher-boiling fol reaction products, e.g. B. the products of aldol condensation, be used. If desired, one can be added to each used catalyst / co-catalyst system coordinated Lö solvent or solvent mixture can be used. So can z. B. with sufficient hydrophilized ligands water and Alcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. can be used. Appropriate solution ketones, such as acetone and methyl ethyl ketone, aliphatic and aromatic hydrocarbons, such as hexane, Benzene, toluene, xylene etc.

The method according to the invention advantageously enables all common with the hydroformylation of olefins and olefin mixtures the most effective use possible in a reaction cascade available reaction space. By the fiction it is the reaction procedure used in "inverse cascade" possible, both lighter and harder to hydroformylated oils fine, and in particular mixtures containing both species, the Undergo hydroformylation. It is after the invent Process according to the invention by feeding the hydroformy lating olefins in the second reaction stage of a cascade and the subsequent separation stage with a return of only the non-hydroformylated olefins in the first stage of the cascade possible, the residence time and the thermal load of the gebil deten hydroformylation products, d. H. of the aldehydes formed and / or keep alcohols as low as possible. So it works in general, the formation of undesirable, high-boiling side products in the process according to the invention from To minimize known processes.

The invention is illustrated by the following, not restrictive Examples explained in more detail.

Examples

Two two-stage reactor cascades with feedback are compared tion of the catalyst and the unreacted olefin.

The feed flow of fresh olefin was 700 g / h in both cases.  

In comparative case I, which is not according to the invention, the fresh oil was introduced into the first reactor and reacted there with an approximately 10 mol% excess of synthesis gas (CO / H ₂ 1: 1). The discharge from reactor 1 was then passed directly into the second reactor of the cascade without further processing and was subjected to a second hydroformylation with an approximately 10 mol% excess of synthesis gas. After the synthesis gas had been separated off, the reaction product from the second reactor was separated by distillation into a catalyst product, a hydroformylation product and a fraction containing the unreacted olefin. The fractions containing the catalyst and the unreacted olefin are returned to the first reactor. 10% by weight are removed from the olefin recycle stream in order to remove inert components (paraffins) from the circuit.

In case II according to the invention, the olefin is fed in in the second reactor of the cascade.

In both cases I and II the compositions are fresh olefins as well as the catalyst amounts, the catalyst mass flow and the rhodium concentration of the catalyst stream is the same.

A continuously operated reaction system consisting of two stirred reactors (liquid volume 1.15 l each) was used for the hydroformylation. Both reactors were operated at 150 ° C and a synthesis gas pressure (CO / H ₂ 1: 1) of 280 bar. As an olefin, a mixture of octene isomers (6% by weight of n-octene, 57% by weight of isomeric methylheptenes, 37% by weight of isomeric dimethylhexenes) and as catalyst a high-boiling solution derived from a C ₉ aldehyde with a rhodium content of 350 mg / kg and a content of dissolved modified polyethyleneimine (original weight-average molecular weight found about 25000 g / mol, reaction of about 60% of the amino groups contained with lauric acid, nitrogen content 9.3% by weight). The polyethyleneimine content was determined analytically via the nitrogen content according to Kjedahl.

The reaction discharge from the second reactor was depressurized in a separation stage consisting of a wiper blade evaporator fer and a column, separated. The residue of Wiper blade evaporator a liquid catalyst-containing fraction made of rhodium catalyst and polyethyleneimine cocatalyst in high-boiling reaction by-products and with a low Residual content of non-separated aldehydes and alcohols, iso profiled. The top product of the wiper blade evaporator was then eats in a column in a product-containing aldehyde and alcohol wood fraction and an unreacted olefin-containing fraction  separated. The catalyst-containing fraction (nitrogen content approx. 0.9 g / 100 g, rhodium concentration approx. 350 mg / kg) and the olefin-containing fraction were in the first reactor of the cascade fed. The catalyst flow was 50 g / h.

Results

If the ratio of the amount of olefins converted in a reactor to the amount of olefins introduced into the respective reactor is defined as conversion, the following values result in comparison case I:

The following values result in case II according to the invention:

The return flow of unreacted olefin was in Ver likewise I 413.4 g / h and in case II according to the invention 250.1 g / h. This proves that in the case according to the invention in both Reactors have a higher turnover per run of harder to hydro formylating dimethylhexenes is achieved than in the comparison case. Furthermore, in the case of the invention, the amount of olefin is that must be returned, advantageously less.

Claims (10)

1. A process for the hydroformylation of olefins by reaction with carbon monoxide and hydrogen in the presence of a hydroformylation catalyst in a reaction system which comprises two reaction stages R ₁ and R ₂ , characterized in that

• - feeding into the reaction stage R ₂ is an olefin-comprising feed, carbon monoxide, hydrogen, and the effluent from the stage R ₁ and partially catalytically reacted,
• separates the discharge from reaction stage R ₂ in a separation stage into a catalyst-containing liquid fraction F1, a product-containing fraction F2 and an unreacted olefin fraction F3,
• partly or completely feeds fraction F3 and optionally partly or completely fraction F1 as well as carbon monoxide and / or hydrogen into reaction step R ₁ and converts them catalytically,
• - Feeds the discharge from the reaction stage R ₁ into the reaction stage R ₂ .

2. The method according to claim 1, characterized in that the conversion based on the olefin amount of the olefin-containing feed in the reaction stage R _{2 is} at least 50% by weight, preferably at least 60% by weight. 3. The method according to any one of the preceding claims, characterized characterized that the product-containing fraction F2 at most 5% by weight, preferably at most 1% by weight of unreacted oil fin contains. 4. The method according to any one of the preceding claims, characterized characterized that the olefin-containing fraction F3 at most 20 wt .-%, preferably at most 5 wt .-% hydroformylation contains products.   5. The method according to any one of the preceding claims, characterized in that 1 to 100 wt .-%, preferably 10 to 100 wt .-%, in particular 20 to 99 wt .-% of the catalyst-containing fraction F1 is fed into the reaction stage R ₁ . 6. The method according to claim 5, characterized in that the fraction F1 is partly fed into the reaction stage R ₂ . 7. The method according to any one of the preceding claims, characterized in that the weight ratio of the fraction F3 fed into the reaction stage R ₁ to the fed fraction F1 in a range from 10: 1 to 1:10, preferably 5: 1 to 1 : 5, lies. 8. The method according to any one of the preceding claims, characterized in that the ratio of mass of the hydroformylation catalyst per mass of reactor charge from reaction stage R ₂ to reaction stage R _{1 is} in a range from 1: 1 to 1:10. 9. The method according to any one of the preceding claims, characterized in that the residence time in reaction stage R ₁ is 1 to 10 times, preferably 1 to 5 times, the Ver residence time in reaction stage R ₂ . 10. The method according to any one of the preceding claims, characterized characterized in that an olefin mixture is used as the olefin will be at least an easy and at least a difficult one comprises hydroformylatable olefin.