阅读说明：本技术 在气相中制备短链烯烃的方法 (Process for preparing short-chain olefins in the gas phase ) 是由 J·哈塞尔贝格 R·弗兰克 F·施滕格 P·克赖斯 C·黑希特 M·O·克里斯滕 于 2019-09-30 设计创作，主要内容包括：本发明涉及将短链烯烃特别是C2-C5烯烃加氢甲酰化的方法,其中催化剂体系以非均相化形式存在于由多孔陶瓷材料组成的载体上,本发明还涉及进行该方法的设备。(The invention relates to a method for hydroformylating short-chain olefins, in particular C2-C5 olefins, in which the catalyst system is present in heterogeneous form on a support consisting of a porous ceramic material, and to a device for carrying out the method.)

1. Process for the hydroformylation of C2-C8 olefins in a reaction zone using a heterogenized catalyst system, wherein the process is characterized in that

Passing a gaseous feed mixture containing C2-C8 olefins, together with synthesis gas, through a support consisting of a porous ceramic material, on which is in heterogeneous form a catalyst system comprising a metal of group 8 or 9 of the periodic table of the elements, at least one organic phosphorus-containing ligand, a stabilizer and optionally an ionic liquid; and

the support is in the form of a powder, in the form of granules or in the form of pellets and consists of a carbide, nitride or silicide material or a mixture thereof, on which a washcoat of a ceramic material, which is the same or different with respect to the ceramic material of the support, is applied.

2. The process according to claim 1, wherein the organophosphorus ligand in the hydroformylation catalyst system preferably has the general formula (VI)

R'–A–R”–A–R”' (VI)

Wherein R ', R ' and R ' are each an organic group, provided that R ' and R ' are not the same and each A is bridged-O-P (-O)₂-a group wherein two of the three oxygen atoms-O-are each bonded to an R 'group and an R' "group.

3. The method of claim 1 or 2, wherein the stabilizer is an organic amine compound containing at least one 2,2,6, 6-tetramethylpiperidine unit of formula (I):

4. the method of any one of claims 1-3, wherein the nitride ceramic is selected from the group consisting of silicon nitride, boron nitride, aluminum nitride, and mixtures thereof; the carbide ceramic is selected from silicon carbide, boron carbide, tungsten carbide or a mixture thereof; and the silicide ceramic is molybdenum silicide.

5. The method of claim 4, wherein the support is comprised of a carbide ceramic.

6. A method according to claim 5 wherein the support consists of silicon carbide.

7. The method according to any one of claims 1-6, wherein the washcoat is present on the support in an amount of ≤ 20 wt% based on the total amount of support.

8. The method of any one of claims 1-7, wherein the support has a median particle diameter (d50) of 0.1mm-7 mm.

9. The process according to any one of claims 1 to 8, wherein the hydroformylation is carried out at a temperature of from 65 to 200 ℃, preferably from 75 to 175 ℃, more preferably from 85 to 150 ℃.

10. The process according to any of claims 1 to 9, wherein the pressure in the hydroformylation reaction is not more than 35bar, preferably not more than 30bar, more preferably not more than 25 bar.

11. The process of any one of claims 1-10, wherein the catalyst system does not comprise any ionic liquid.

Technical Field

The invention relates to a method for hydroformylating short-chain olefins, in particular C2-C5 olefins, wherein the catalyst system is present in heterogeneous form on a support of a porous ceramic material, and to a device for carrying out the method.

Background

Hydroformylation is one of the most important reactions in industrial scale chemistry, with millions of tons of worldwide production capacity per year. Hydroformylation involves the reaction of olefins (olephins) with a mixture of carbon monoxide and hydrogen (also known as synthesis gas or syngas) using a catalyst to produce aldehydes, which are important and valuable intermediates in the production of chemical bulk products such as alcohols, esters or plasticizers.

Hydroformylation is carried out on an industrial scale exclusively under homogeneous catalysis. Soluble transition metal catalyst systems are typically based on cobalt or rhodium, which are often used in conjunction with phosphorus-containing ligands (e.g., phosphines or phosphites) for the hydroformylation of relatively short-chain olefins.

There are various problems in the known processes, which are associated in particular with the fact that rhodium and cobalt and their compounds are relatively expensive. In order to avoid as far as possible the loss of catalyst during the hydroformylation, for example by means of very complicated catalyst recovery steps, there is a high level of energy consumption and complicated chemical engineering. Furthermore, the product purification steps become more and more complicated to ensure that as little catalyst remains as possible in the product.

Other problems in the known homogeneous catalytic processes are the stability of the ligand (which must withstand the hydroformylation conditions, such as temperature, pressure, pH, etc.) and the consumption of the solvent used in the process, which can be compensated by replenishment.

In order to solve the above-mentioned problems in homogeneously catalyzed hydroformylation, hydroformylation processes have been developed in which the catalyst system is heterogenized, in particular by immobilization on a support material (see introductory discussion of WO 2015/028284A 1). The terms "heterogenising" and "fixing" are therefore to be understood as meaning the fixing of the catalyst by forming a thin liquid film on the surface and/or in the pores of a solid support material by means of an ionic liquid, and without a reaction solution which homogeneously dissolves the catalyst in the conventional sense.

With regard to the immobilization/heterogenisation, WO 2015/028284a1, which has already been mentioned, discloses so-called SILP systems (SILP ═ supported ionic liquid phase), in which catalyst systems with rhodium, iridium or cobalt as central atoms are immobilized using ionic liquids, in particular on porous silica supports.

However, a problem with the known SILP systems is that after a certain service life, a significantly reduced catalyst activity and thus a reduced conversion can be observed. This can be attributed to various influences, such as condensation of the product in the pores and corresponding further reactions, such as aldol condensation, or the formation of water, which can lead to deactivation of the ligand, formation of by-products and/or flooding of the pores, with the result that the catalyst can be discharged.

Disclosure of Invention

It is therefore an object of the present invention to provide a process for the hydroformylation of olefins which does not have the abovementioned problems and in particular leads to an increase in the conversion and service life of the catalyst.

The problem is solved according to claim 1 in that a catalyst system is used in the hydroformylation, wherein the catalyst system is in heterogeneous form on a support in the form of a powder, in the form of a granular material or in the form of pellets and consisting of a porous ceramic material.

Accordingly, the present invention provides a process for the hydroformylation of C2 to C5 olefins in a reaction zone using a heterogenized catalyst system, wherein the process is characterized in that

Passing a gaseous feed mixture comprising C2-C8 olefins, together with synthesis gas, through a support composed of a porous ceramic material, on which support a catalyst system is in a non-homogeneous form, the catalyst system comprising a metal of group 8 or 9 of the periodic table of the elements, at least one organic phosphorus-containing ligand, a stabilizer and optionally an ionic liquid; and

support, wherein the support is in the form of a powder, in the form of a granular material or in the form of pellets and consists of a carbide, nitride or silicide material or a mixture thereof, onto which a washcoat (washcoat) of the same or a different ceramic material with respect to the ceramic material of the support has been applied.

The first feed mixture used may be any mixture comprising C2 to C5 olefins, in particular ethylene, propylene, 1-butene, 2-butene, 1-pentene or 2-pentene as reactants. The amount of olefin in the feed mixture should of course be sufficiently high to enable the hydroformylation reaction to be carried out economically. This includes, in particular, industrial mixtures from the petrochemical industry, such as raffinate streams (raffinate I, II or III) or crude butanes. According to the invention, the crude butane comprises from 5% to 40% by weight of butenes, preferably from 20% to 40% by weight of butenes (butenes consisting of from 1% to 20% by weight of 1-butene and from 80% to 99% by weight of 2-butenes) and from 60% to 95% by weight of butanes, preferably from 60% to 80% by weight of butanes.

The reaction zone comprises at least one reactor in which the hydroformylation according to the invention is carried out and in which a support with a heterogenising catalyst system is placed. In another embodiment of the invention, the reaction zone comprises a plurality of reactors, which may be connected in parallel or in series. Preferably, in this case, the reactors are connected in parallel and used alternately. The hydroformylation is carried out using at least one reactor (a), i.e.the reactor is in operation. At least one further reactor (b) is in a waiting state in which no hydroformylation is carried out. This is to be understood as meaning that, as soon as the catalyst activity in the reactor (a) in operation is no longer sufficient, the stream of the feed mixture is switched from this reactor (a) to the next reactor (b) in a waiting state, from which this reactor (b) begins to operate. The reactor (a) is then switched to a regeneration mode in which the catalyst system is regenerated or the support is re-impregnated as described below, and then switched to a standby position until the reactor is put back into operation. The principle can also be applied to 3 or more reactors, where at least one reactor is in operation, one or more reactors are simultaneously in standby mode and one or more reactors are simultaneously in regeneration mode.

The hydroformylation is preferably carried out under the following conditions: the temperature in the hydroformylation should be in the range from 65 to 200 ℃, preferably from 75 to 175 ℃ and particularly preferably from 85 to 150 ℃. During the hydroformylation, the pressure should not exceed 35bar, preferably not exceed 30bar, particularly preferably not exceed 25 bar. The molar ratio between synthesis gas and feed mixture should be between 6:1 and 1:1, preferably between 5:1 and 3: 1. Optionally, the feed mixture may be diluted with an inert gas, for example with an alkane present in the industrial hydrocarbon stream.

The catalyst system used in the hydroformylation process according to the invention preferably comprises a transition metal from group 8 or 9 of the periodic Table of the elements, in particular iron, ruthenium, iridium, cobalt or rhodium, particularly preferably cobalt and rhodium, at least one organic phosphorus-containing ligand, a stabilizer and optionally an ionic liquid.

The stabilizer is preferably an organic amine compound, particularly preferably an organic amine compound comprising at least one 2,2,6, 6-tetramethylpiperidine unit of the formula (I):

in a particularly preferred embodiment of the present invention, the stabilizer is selected from the compounds of the following formulae (I.1), (I.2), (I.3), (I.4), (I.5), (I.6), (I.7) and (I.8):

wherein n is an integer from 1 to 20;

wherein n is an integer from 1 to 12;

wherein n is an integer from 1 to 17;

wherein R is a C6-C20 alkyl group.

The ionic liquids optionally present in the context of the present invention are virtually anhydrous (water content < 1.5% by weight, based on the total amount of ionic liquid) liquids which are in liquid form at standard pressure (1.01325bar) and preferably at 25 ℃. The ionic liquid preferably consists of more than 98% by weight of ions.

In a preferred embodiment, the anion of the ionic liquid is selected from the group consisting of tetrafluoroborate [ BF4]^-(ii) a Hexafluorophosphate [ PF6]^-(ii) a Dicyanamide anion (Dicyanamide) [ N (CN) ]₂]^-(ii) a Bis (trifluoromethylsulfonyl) imido anion [ NTf₂]^-(ii) a Tricyanomethyl anion [ C (CN) ]₃]^-(ii) a Tetracyanoborate [ B (CN)₄]^-(ii) a Halogen ion (especially Cl)^-、Br^-、F^-、I^-) (ii) a HexafluoroantimonyAcid radical [ SbF₆]^-(ii) a Hexafluoroarsenate [ AsF ]₆]^-(ii) a Sulfate radical [ SO ]₄]^2-(ii) a Tosylate [ C ]₇H₇SO₃]^-(ii) a Triflate CF₃SO₃ ^-(ii) a Perfluorobutanesulfonate [ C₄F₉SO₃]^-(ii) a Tris- (pentafluoroethyl) -trifluorophosphate [ PF₃(C₂F₅)₃]^-(ii) a Thiocyanate radical [ SCN]^-(ii) a Carbonate radical [ CO ]₃]^2-；[RA-COO]^-；[RA-SO₃]^-；[RA-SO₄]^-；[RAPO₄RB]^-And [ (RA-SO)₂)₂N]^-Wherein RA and RB may be the same as or different from each other, and are each a linear or branched aliphatic or alicyclic alkyl group having 1 to 12 carbon atoms, a perfluoroalkyl group, or an aryl group which may be substituted with one or more halogen atoms in place of C5 to C18.

The cation of the ionic liquid is preferably selected from the group consisting of the formula [ NR ]¹R²R³R⁴]⁺Of quaternary ammonium cation of (2), wherein R¹、R²、R³、R⁴Independently of one another, C1-C8 alkyl; general formula [ PR¹R²R³R⁴]⁺Phosphonium cation of (2), wherein R¹，R²，R³，R⁴Independently of one another, C1-C8 alkyl; imidazolium cations of the general formula (II)

Wherein R is¹、R²、R³And R⁴Independently of one another, H or C1-C8 alkyl, C1-C6 alkoxy, optionally substituted C1-C6 aminoalkyl or optionally substituted C5-C12 aryl;

pyridinium cations of the general formula (III)

Wherein R is¹And R²Independently of one another, H or C1-C8 alkyl, C1-C6 alkoxy, optionally substituted C1-C6 aminoalkyl or optionally substituted C5-C12 aryl;

pyrazolium cations of the general formula (IV)

Wherein R is¹And R²Independently of one another, H or C1-C8 alkyl, C1-C6 alkoxy, optionally substituted C1-C6 aminoalkyl or optionally substituted C5-C12 aryl;

triazolium cations of the general formula (V)

Wherein R is¹And R²And/or R³Independently of one another, H or C1-C8 alkyl, C1-C6 alkoxy, optionally substituted C1-C6 aminoalkyl or optionally substituted C5-C12 aryl.

In a preferred embodiment, the cation of the ionic liquid is R which has a corresponding definition according to the above formula (II)¹-R⁴Imidazolium cations of the group. In a particularly preferred embodiment, the ionic liquid is selected from the group consisting of 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-ethyl-3-methylimidazolium ethyl sulfate, trioctylmethylammonium bis (trifluoromethylsulfonyl) imide and 1-butyl-3-methylimidazolium octyl sulfate.

In the catalyst system of the present invention, the ionic liquid optionally present serves as a support solution for the transition metal catalyst with ligand and the stabilizer. It is important here that the ionic liquid can absorb (i.e. dissolve) the reactants (feed olefin and synthesis gas) well and has a relatively low vapour pressure, so that the catalyst system also exists as a liquid reservoir at high temperatures. However, it has surprisingly been found that the stabilizer can also form a stable liquid film in the pores of the carrier, thus enabling partial or complete replacement of the ionic liquid. In a preferred embodiment, the catalyst system does not comprise any ionic liquid.

For all membrane-forming components, i.e. in this case the ionic liquid and/or the stabiliser, the gas solubility of the reactants should be greater than the gas solubility of the product. Only in this way it is possible to achieve a partial physical separation between the reactant olefin used and the product aldehyde formed. In principle, other film-forming substances can also be considered for this purpose, but it should be ensured that the formation of high boilers is not increased and/or the resupply of the reactant olefins is not limited.

The organic phosphorus-containing ligands used in the catalyst systems according to the invention preferably have the general formula (VI)

R'-A-R”-A-R”' (VI)

Wherein R ', R "and R'" are all organic radicals and each A is a bridged-O-P (-O)₂-a group wherein two of the three oxygen atoms-O-are each bonded to a R 'group and a R' "group, with the proviso that R 'and R'" are not identical. The organic groups R ', R "and R'" preferably do not contain any terminal trialkoxysilane groups.

In a preferred embodiment, R ', R "and R '" in the compound of formula (VI) are preferably selected from substituted or unsubstituted 1,1' -biphenyl, 1' -binaphthyl and o-phenyl, in particular from substituted or unsubstituted 1,1' -biphenyl, with the proviso that R ' and R ' "are not identical. More preferably, the substituted 1,1 '-biphenylyl group has an alkyl and/or alkoxy group, in particular a C1-C4 alkyl group, more preferably a tert-butyl and/or methyl group, preferably a C1-C5 alkoxy group, particularly preferably a methoxy group, in the 3,3' -and/or 5,5 '-position of the 1,1' -biphenylyl skeleton.

According to the invention, the above-mentioned catalyst system is in a heterogeneous form on a support of a porous ceramic material. In the context of the present invention, the expression "heterogeneously on a support" is understood to mean the immobilization of the catalyst system by forming a thin solid or liquid film on the inner and/or outer surface of the solid support material by means of the stabilizer and/or optionally the ionic liquid. The membrane may also be solid at room temperature and liquid under the reaction conditions.

The inner surface of the solid support material comprises in particular the inner surface area of the pores. The concept "fixed" includes the following two cases: the case where the catalyst system and/or catalytically active species are in dissolved form in a solid or liquid film, and the case where the stabilizer acts as a viscosifier or catalyst system adsorbed on the surface but not chemically or covalently bonded to the surface.

According to the invention, there is therefore no reaction solution in the conventional sense in which the catalyst is homogeneously dissolved; instead, the catalyst system is dispersed on the surface and/or in the pores of the support.

The porous support material is preferably selected from the group consisting of nitride ceramics, carbide ceramics, silicide ceramics and mixtures thereof, such as carbonitride materials.

The nitride ceramic is preferably selected from the group consisting of silicon nitride, boron nitride, aluminum nitride, and mixtures thereof. The carbide ceramic is preferably selected from silicon carbide, boron carbide, tungsten carbide or mixtures thereof. Also contemplated are mixtures of carbide ceramics and nitride ceramics, known as carbonitrides. The silicide ceramic is preferably molybdenum silicide. The support to which the catalyst system is applied according to the invention preferably consists of a carbide ceramic, more preferably of silicon carbide.

According to the invention, the support is preferably in the form of a powder, a granular material or in the form of pellets. The median particle diameter (D50) of the carrier may be from 0.1mm to 7mm, preferably from 0.3 to 6mm, more preferably from 0.5mm to 5 mm. The median particle diameter can be determined by imaging methods, in particular by the methods specified in the standards ISO 13322-1 (date: 2004-12-01) and ISO 13322-2 (date: 2006-11-01). The carrier can be produced in powder form, in the form of a granular material or in the form of pellets by methods known to the person skilled in the art. This can be done, for example, by mechanically crushing a single piece of carbide, nitride or silicide material or a mixture thereof, for example with a jaw crusher, and adjusting the particle size of the obtained crushed granular material by sieving.

Furthermore, the support or the particles of powder, granular material or pellet particles of the ceramic material are porous, i.e. the support has pores. The catalyst system according to the invention is also present in these pores, in particular as a liquid or solid film. The pore diameter is preferably in the range of 0.9nm to 30 μm, preferably in the range of 10nm to 25 μm, more preferably in the range of 70nm to 20 μm. The pore diameter can be determined by nitrogen adsorption or mercury porosimetry according to DIN 66133 (1993-06).

In a preferred embodiment, the support has at least partially continuous pores extending from one surface to the other. It is also possible that a plurality of holes are connected to each other, thus forming a single continuous hole as a whole.

The preparation of the support from the porous ceramic material, on which the catalyst system is present heterogeneously, is as follows: the support provided, which is composed of a ceramic material and is in the form of a powder, granular material or pellets, is additionally coated with a so-called washcoat which consists of the same or a different ceramic material, preferably silicon oxide, with respect to the ceramic material of the support. The washcoat itself may be porous or non-porous; the washcoat is preferably non-porous. The particle size of the carrier coating is preferably from 5nm to 3 μm, preferably from 7nm to 700 nm. A washcoat (washcoat) is used to introduce or create the desired pore size and/or to increase the surface area of the support. The application of the carrier coating can be carried out in particular by immersion (dip coating) into a coating solution containing the ceramic material of the coating (possibly also used as precursor). The washcoat is present on the support in an amount of 20 wt.% or less, preferably 15 wt.% or less, more preferably 10 wt.% or less, based on the total amount of support.

The catalyst system is applied to the support thus produced with the applied coating. To this end, a catalyst solution is first prepared by mixing, in particular at room temperature and ambient pressure, which catalyst solution comprises at least one organic phosphorus-containing ligand, at least one metal precursor (e.g. chloride, oxide, carboxylate of the corresponding metal), at least one stabilizer and at least one solvent. Optionally, an ionic liquid may be used in the preparation of the catalyst system, but the catalyst solution may also be explicitly prepared without an ionic liquid. The preparation of the catalyst solution should be carried out in particular under an inert environment, for example in a glove box. In this case, "inert environment" refers to an atmosphere that is substantially free of water and oxygen.

The solvent may be selected from all solvent types (protic, aprotic, polar or apolar). A prerequisite for the solvent is the solubility of the catalyst system (ligand, metal precursor, stabilizer and optionally ionic liquid) and preferably also the high boilers produced in the hydroformylation. In the fixation step, the solubility can be increased by heating.

The solvent is preferably aprotic and polar, such as acetonitrile and ethyl acetate, or aprotic and nonpolar, such as THF and diethyl ether. Chlorinated hydrocarbons, such as methylene chloride, may also be used as a solvent.

The catalyst solution thus prepared is then brought into contact with the support (optionally including a washcoat), for example directly in the reactor (in situ impregnation), for example by immersion (dip-coating) or by filling a pressure vessel. If the catalyst solution is applied outside the reactor, it is of course necessary to remount the support into the reactor after removal of the solvent. Preferably, the catalyst solution is applied directly to the coated support in the reactor, since thereby possibly time-consuming mounting and dismounting steps and possible contamination of the catalyst can be avoided.

In the case of in situ impregnation, the reactor is purged with an inert gas, such as a noble gas, alkane or nitrogen, prior to filling. Purging may be carried out at from 1 to 25bar, preferably at a slightly positive pressure of from 20 to 90mbar, more preferably from 30 to 60mbar, above the standard pressure. The reactor may be cooled prior to purging with an inert gas to prevent the solvent in the catalyst solution to be introduced from immediately evaporating. However, if the boiling temperature of the solvent is higher than the reactor temperature, cooling of the reactor may be omitted.

After purging with inert gas, the pressure present can be released, for example by means of a pressure control system, preferably until the reactor is pressureless, i.e. at ambient pressure (i.e. 1 bar). In addition, a vacuum may also be generated in the reactor, for example, by means of a vacuum pump. In one embodiment of the invention, the reactor may be purged again with inert gas as described above after releasing the pressure or after pulling a vacuum. This pressure release/evacuation and re-purge operation can be repeated as often as necessary.

To fill the reactor, the catalyst solution is first charged into a pressure vessel and is preferably pressurized to a positive inert gas pressure of 1 to 25bar, more preferably a slightly positive inert gas pressure of 20 to 90mbar, preferably 30 to 60mbar, above the reactor pressure. The inert gas may be a noble gas, an alkane such as butane or nitrogen. The catalyst solution is then introduced into the reactor under a positive pressure applied to the pressure vessel, in particular in a pressure-driven manner. The pressure in the pressure vessel during filling should be higher than the pressure in the reactor. The temperature may be in the range of 20-150 ℃ and the pressure 1-25 bar.

Another filling method is to keep the reactor under reduced pressure after purging with an inert gas and to draw the catalyst solution into the reactor by reducing the pressure. For preparing the catalyst solution, a solvent boiling under a normal vacuum or reduced pressure and at a normal temperature should be used.

The reactor may be filled with the catalyst solution through the normal inlet/outlet. Liquid distributors or nozzles in the reactor can ensure a uniform distribution of the catalyst liquid, and optionally pressure drop internals or regulators for the metering rate can also ensure a uniform distribution of the catalyst liquid.

After application of the catalyst system, the solvent is removed. This involves first discharging the remaining catalyst solution through the reactor outlet. Then, the solvent residue remaining in the reactor was evaporated by adjusting the pressure or raising the temperature. In another embodiment, the pressure can also be adjusted with a simultaneous increase in temperature. Depending on the solvent, the temperature may be from 20 to 150 ℃. Depending on the solvent, the pressure can be adjusted to a high vacuum (10)^-3To 10^-7mbar), but elevated pressures of a few mbar to a few bar can also be considered, depending on the solvent and the temperature.

The stabilizer and the ionic liquid, if present, are retained on the support in heterogeneous form together with the catalyst composed of the transition metal, in particular cobalt or rhodium, and the organophosphorus ligand.

The catalyst system can be applied to the support directly in the reactor (in situ) or outside the reactor. Another problem is that the carrier must always be transported with air excluded, which is difficult to achieve during mounting and dismounting. Thus, in a preferred embodiment of the present invention, the catalyst system is applied directly in the reactor (i.e. in situ). Immediately after removal of the solvent, the reactor can be used and charged with the feed mixture. This has the advantage that no installation and dismantling steps are required which are time consuming and may lead to excessive down time of the reactor. Furthermore, the size of the carrier is no longer limited in that case, since a suitable space with an inert environment can be obtained in a specific size. The size of the support can be freely chosen depending on the reactor design.

After both the application of the catalyst system to the support and the removal of the solvent have been completed, the plant, in particular the reactor, can be started up by a two-stage or more-stage start-up procedure, i.e. put into operation.

The purpose of the start-up procedure is a gentle activation of the catalyst system and a reduction of the maximum starting activity of the catalyst to extend the service life of the catalyst system. Furthermore, the start-up procedure is intended to prevent the formation of a liquid phase, as this may lead to deactivation, blocking and/or elution of the catalyst system. This is because, in particular in the case of the start-up of freshly prepared catalyst systems (on a support) with concentrated reactants, maximum reaction conversions can be achieved, which are also associated with maximum formation of by-products (high boilers). If the proportion of high-boiling by-products, depending on the operating conditions (pressure and temperature), exceeds a certain value, this can lead, owing to the vapor pressure of the individual components, depending on the mixture present, to the formation of a liquid phase which can damage, block or rinse off the catalyst system.

According to the invention, the activation of the catalyst system is preferably effected in such a way that the conversion increases over a prolonged period of time. Thus, for any combination of pressure, temperature and composition of the feed mixture, a maximum allowable conversion rate that should not be exceeded for by-product formation can be calculated so as not to allow the above-mentioned problems to occur. The conversion for by-product formation can also be determined from the conversion for product aldehyde formation (which depends on the aldehyde concentration), which means that the start-up procedure is guided by the maximum conversion of the feed olefin.

Under the known long-term operating conditions of the reactor, which enable a reliable conversion of the feed olefins of 20 to 95%, preferably 80 to 95%, to be achieved, the start-up procedure can be such that: the composition of the feed mixture to the reactor is gradually changed without exceeding the maximum conversion of the feed olefins.

In this case, the composition of the feed mixture which ensures reliable conversion of the olefins under long-term operating conditions can be varied such that the olefin content and/or the synthesis gas content is increased in at least two, preferably more than three, in particular four or more, stages at constant volume flow rates without exceeding the maximum conversion of the feed olefins. To this end, inert gases, such as N, may be supplied to the industrial feed mixture and the synthesis gas mixture in the first stage(s)₂Argon, helium, and the like.

The catalyst activity can decrease with increasing operating time, for example due to enrichment of high boilers and/or coverage or deactivation of the active centers. High boiling point materials can lead to increased condensation in the pores, allowing the reactant olefins to reach the pores more slowly (if at all). Secondly, some by-products may lead to decomposition of the catalyst system, which also reduces the activity of the catalyst. The reduction in catalyst activity can be determined, for example, by a reduction in conversion or selectivity, in particular by raman spectroscopy, gas chromatography or appropriate analysis of Mass Flow Meters (MFMs). Another option is model-based catalyst activity monitoring. This would be a method independent of the operating conditions for monitoring catalyst activity and to infer progress and thus support a review/regeneration plan.

In the case of insufficient catalyst activity, it is possible to replace the catalyst system in heterogeneous form on a porous ceramic support. To this end, the catalyst or support may be purged once or more than once with solvent in the reactor. The purge can cause the catalyst system to be stripped and removed. The solvent may be one of the solvents mentioned for the preparation of the catalyst solution. The temperature during solvent purging may be 20-150 ℃. The pressure at which the solvent is purged may additionally be 1 to 25 bar.

After purging, the support is re-impregnated one or more times, in particular by in situ impregnation of the support as described above. Thus, the impregnation is carried out again in situ, so that a heterogenised catalyst system is newly applied. The in situ re-impregnation may be carried out under exactly the same conditions as the first in situ impregnation described above.

Due to the fact that the catalyst system can be completely replaced by purging and reapplication, these steps can be repeated continuously as soon as the catalyst activity decreases again. A further advantage is that high boilers and product aldehydes as well as decomposition products of the catalyst system can be discharged. However, it should be ensured that the properties of the support are not impaired by destabilization and in situ re-impregnation. Otherwise, replacement of the porous ceramic support must be performed.

Another option is to replace the entire porous ceramic support on which the catalyst system is present in heterogenised form. The supported catalyst system present in heterogeneous form (removed from the reactor) can then be replaced outside the reactor as described above and stored until the next installation and use in the reactor. As mentioned above, an inert environment is required for the application of the catalyst system, and therefore handling and storage during the described method of dismantling and installing the support should take place under corresponding conditions.

Preferably, a gaseous output comprising at least a portion of the product aldehyde formed and at least a portion of the unconverted olefin is continuously withdrawn from the reaction zone in which the hydroformylation according to the invention is carried out. The gaseous output may be subjected to one or more physical separation steps, wherein the gaseous output is separated into at least one phase rich in unconverted olefin and at least one phase rich in product aldehyde.

The physical separation can be carried out by known physical separation methods, such as concentration, distillation, centrifugation, nanofiltration or a combination of two or more of these methods, preferably concentration or distillation.

In the case of a multistage physical separation, the product aldehyde-rich phase formed in the first physical separation is sent to a second physical separation, in particular downstream removal of aldehydes, where the product aldehyde is separated from the other species present in this phase (usually alkanes and reactant olefins). The phase enriched in unconverted olefin can be recycled to the hydroformylation stage or, in the case of a multistage configuration, to one of the hydroformylation stages, in order to also hydroformylate the olefin present therein to the product aldehyde.

In the physical separation, and in the phase in question, it is also possible to take off a purge gas stream having the same or at least a similar composition to that of the phase enriched in unconverted olefin. The purge stream may also be directed to a second physical separation or aldehyde removal to remove product aldehydes present therein and to purge impurities (e.g., nitrogen in the syngas) or inerts (e.g., alkanes in the feed mixture) from the system. Impurities or inerts can usually be removed in a second physical separation as volatile substances, for example at the top of the column.

The present invention still further provides an apparatus by means of which the process according to the invention can be carried out, which apparatus comprises in particular a reactor in which the hydroformylation stage according to the invention is carried out. In addition, the apparatus can comprise a physical separation unit with which the gaseous output from the hydroformylation stage is separated into at least one phase which is rich in unconverted olefin and at least one phase which is rich in product aldehyde, wherein the physical separation unit is arranged downstream of the hydroformylation according to the invention. Downstream of the first physical separation, there may be a second physical separation unit, in particular an aldehyde removal unit for separating the product aldehyde.

Without further elaboration, it is assumed that a person skilled in the art will be able to utilize the above description to the fullest extent possible. Accordingly, the preferred embodiments and examples are to be construed as merely illustrative, and not a limitation of the disclosure in any way whatsoever.

The present invention will be more specifically explained below with reference to examples. Alternative embodiments of the invention are similarly available.

Detailed Description

Example (b):

experiment 1: preparation and analysis of the catalyst System according to the invention

The starting material for the support was monolithic silicon carbide having a length of about 20cm and a diameter of about 25 mm. The monolith was crushed with a jaw crusher having a gap width of 2 mm. The crushed support is then sieved to a target particle size of 2-3.15mm and coated with a carrier coating (SiO)₂) And (4) preprocessing. The granular material thus produced was then introduced into a circular reactor sleeve having a length of 20cm and a diameter of one inch (about 2.54cm), and glass beads of similar size were introduced above and below the granular material. The granular material is then mixed with a mixture prepared by mixing in an inert environment (glove box) containing Rh (acac) (CO)₂Bispherphos (ligand), bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate (stabilizer) and dichloromethane as solvent. For this purpose, the catalyst solution was introduced into the reactor at a slightly positive pressure after purging the reactor with nitrogen. After removal of the solvent from the reactor by venting and evaporation, hydroformylation is carried out using a catalyst system which is heterogeneous on a particulate support material.

The feed mixture used was a hydrocarbon stream having the following composition:

	amount (wt%)
		1-butene/isobutene	19.14
Cis-2-butene	19.10
		Trans-2-butene	28.40
N-butane	30.80
		Isobutane	0.02
2-methylbutane	2.50

The feed mixture was introduced into the reactor together with synthesis gas (molar ratio of synthesis gas to feed mixture 3.5:1) at a gas volumetric flow rate of 390ml/min for hydroformylation. The hydroformylation is carried out at a temperature of 120 ℃ and a pressure of 10 bar. The overall conversion of butenes (i.e., the conversion of all butenes present in the feed mixture) and n/iso selectivity (ratio of linear to branched products) is determined by gas chromatography through the product composition.

After an experimental duration of 380 hours, the total conversion of butene was 35% and the n/iso selectivity was 97%.

Experiment 2: preparation and analysis of SILP catalyst systems not in accordance with the invention

The preparation of the catalyst system is analogous to that of the catalytically active composition Rh (II) from WO 2015/028284A 1.

The feed mixture used was a hydrocarbon stream having the following composition:

	amount (wt%)
		1-butene/isobutene	27.40
Cis-2-butene	15.00
		Trans-2-butene	25.00
N-butane	29.50
		Isobutane	0.02
2-methylbutane	3.00

The feed mixture was introduced into the reactor together with synthesis gas (molar ratio of synthesis gas: feed mixture: 3.5:1) at a gas volume flow rate of 390ml/min for hydroformylation. The hydroformylation is carried out at a temperature of 120 ℃ and a pressure of 10 bar. The overall conversion of butenes (i.e., the conversion of all butenes present in the feed mixture) and n/iso selectivity (ratio of linear to branched products) is determined by gas chromatography through the product composition.

After an experimental duration of 380 hours, the total conversion of butenes was 25% and the n/iso selectivity was 93%.

It is therefore evident from a series of experiments that the heterogeneous catalyst system of the present invention has the advantage over the known SILP systems that higher conversions and higher product linearity (n/iso selectivity) can be obtained therewith.