Hydroformylation process of short-chain olefins in the gas phase

Abstract

The present invention relates to a process for hydroformylating short-chain olefins, particularly C2-C8 olefins, in which a catalyst system comprising a metal of Group 8 or 9 of the Periodic Table of the Elements, at least one organophosphorus-containing ligand and a stabilizer is immobilized on a support made of a porous ceramic material, the support consisting of a bed of SiC moldings, and the ratio of the pores having a pore diameter in the range of 10 nm to 1000 nm is 20 to 70% or 25 to 50% with respect to the total amount of the pores of the SiC moldings.

Description

Technical Field

[0001] The project related to this patent application is funded by the European Union (EU) research and innovation program "Horizon 2020" (grant contract number 869896). The present invention relates to a process for hydroformylating short-chain olefins, particularly C2-C8 olefins, wherein a catalyst system comprising a metal of Group 8 or 9 of the Periodic Table, at least one organophosphorus-containing ligand and a stabilizer is immobilized on a support made of a porous ceramic material, the support consisting of a bed of silicon carbide (SiC) formed bodies, and the ratio of pores having a pore diameter in the range of 10 nm to 1000 nm is 20 to 70% or 25 to 50% with respect to the total amount of pores of the SiC formed bodies.

Background Art

[0002] Hydroformylation, with an annual world production capacity of several million tons, is one of the most important reactions in industrial chemistry. In this process, an alkene (olefin) is converted using a catalyst with a mixture of carbon monoxide and hydrogen (also known as synthesis gas or syngas) to form aldehydes, which are important and valuable intermediates in the production of bulk chemical products such as alcohols, esters, and plasticizers. Hydroformylation is carried out almost exclusively with homogeneous catalysts on an industrial scale. Soluble transition metal catalyst systems are usually cobalt- or rhodium-based and are often used for the hydroformylation of short-chain olefins together with phosphorus-containing ligands such as phosphines or phosphites.

[0003] Known methods have various problems, particularly related to the fact that rhodium, cobalt, and their compounds are relatively expensive. To avoid catalyst losses during the hydroformylation process as much as possible, a great deal of energy and process engineering are required, including extremely complex steps such as a catalyst recycling step. Furthermore, the product purification step to ensure that as little catalyst residue remains in the product as possible has become more complex. A further problem with known homogeneous catalyst processes is the stability of the ligands, which must withstand the conditions of hydroformylation such as temperature, pressure, pH value, etc., and the consumption of the solvent used in the process, which must be replenished by subsequent dosing.

[0004] To avoid the above problems in homogeneous-catalyzed hydroformylation, hydroformylation processes have been developed that heterogenize the catalyst system, especially by immobilization on a support material (see the introduction of Patent Document 1). Therefore, the terms "heterogenization" and "immobilization" are understood to mean that the catalyst is immobilized by forming a thin liquid film on the surface and / or within the pores of a solid support material using an ionic liquid, and there is no reaction solution in the conventional sense in which the catalyst is homogeneously dissolved. Hydroformylation processes in which the catalyst is heterogenized on a support material are disclosed, for example, in Patent Documents 1 to 5.

[0005] A problem with known heterogeneous catalyst systems is that the supports used to apply the catalyst are difficult or impossible to obtain commercially. Instead, such supports, for example, monolithic blocks that may still contain flow channels, have to be manufactured specifically and at great expense for this application only. This not only increases costs but also involves the risk that the support is not available and cannot be used immediately. This can lead to production losses. Furthermore, the size of the monolithic structure is limited by its mechanical stability, which imposes limitations on reactor design.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0007] Accordingly, an object of the present invention was to provide a hydroformylation process for olefins that does not have the above problems. More specifically, a support that is easily available and does not need to be specially manufactured for this purpose should be provided.

Means for Solving the Problems

[0008] This problem is solved according to claim 1 of the present application by using a catalyst system for hydroformylation, wherein the catalyst system is immobilized on a support consisting of a bed of SiC formed bodies, and the SiC formed bodies have a ratio of pores with a pore diameter in the range of 10 nm to 1000 nm of 20 to 70%, preferably 25 to 50%, based on the total amount of their pores.

Modes for Carrying Out the Invention

[0009] Accordingly, the present invention is a process for hydroformylating C2 - C8 olefins in a reaction zone using a heterogeneous catalyst system, the process comprising passing a gaseous feed mixture containing C2 - C8 olefins, together with synthesis gas, over a support consisting of a porous ceramic material on which a hydroformylation catalyst system comprising a Group 8 or 9 metal of the Periodic Table of the Elements, at least one organophosphorus-containing ligand, and a stabilizer is immobilized, wherein the bed of the support consists of SiC formed bodies, and the SiC formed bodies have a ratio of pores with a pore diameter in the range of 10 nm to 1000 nm of 20 to 70% or 25 to 50% based on the total amount of their pores, provides a process.

[0010] The feed mixture used may be any mixture containing C2 - C8 olefins as reactants, preferably C2 - C5 olefins, in particular ethene, propene, 1 - butene, 2 - butene, 1 - pentene or 2 - pentene. The amount of olefins in the feed mixture should, of course, be an amount sufficient to enable the hydroformylation reaction to be operated economically. Examples of feed mixtures that can be used in the process according to the invention include, in particular, industrial mixtures from the petrochemical industry, such as raffinate streams (raffinate I, II or III) or crude butane. According to the invention, crude butane contains 5 - 40% by mass of butenes, preferably 20 - 40% by mass of butenes (the butenes consist of 1 - 20% by mass of 1 - butene and 80 - 99% by mass of 2 - butene) and 60 - 95% by mass of butane, preferably 60 - 80% by mass of butane.

[0011] The process according to the invention is carried out in at least one reactor in which the hydroformylation according to the invention takes place. A support comprising a heterogeneous catalyst system is arranged in at least one reactor. In a further embodiment of the invention, the process may also be carried out in 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. An example of a suitable reactor type is a conventional tube - bundle reactor.

[0012] The hydroformylation is preferably carried out under the following conditions: The temperature of the hydroformylation ranges from 65 - 200°C, preferably from 75 - 175°C, more preferably from 85 - 150°C. The temperature may be set by means of a suitable cooling device, such as a cooling jacket. The pressure in the hydroformylation desirably does not exceed 35 bar, preferably 30 bar, particularly preferably 25 bar. The molar ratio of synthesis gas to the feed mixture should be from 6:1 to 1:1, preferably from 5:1 to 3:1. Optionally, the feed mixture may be diluted with an inert gas, such as an alkane present in an industrial hydrocarbon stream. The catalyst system used in the hydroformylation process according to the present invention preferably comprises a transition metal of Group 8 or Group 9 of the Periodic Table of the Elements, particularly iron, ruthenium, iridium, cobalt or rhodium, more preferably cobalt or rhodium, and particularly preferably at least one organic phosphorus-containing ligand and a stabilizer.

[0013] The stabilizer is preferably an organic amine compound, more preferably the following formula (I):

[0014]

Chem.

[0015] In a particularly preferred embodiment of the present invention, the stabilizer is the following formulas (I.1), (I.2), (I.3), (I.4), (I.5), (I.6), (I.7) and (I.8):

[0016]

Chem.

[0017]

Chem.

[0018]

Chem.

[0019]

Chem.

[0020] For all film-forming components, i.e., in this case stabilizers, the gas solubility of the reactants should be better than that of the products. This alone can achieve a partial 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 care should be taken so that no increase in boiling point occurs and / or the resupply of the reactant olefin is reliably restricted.

[0021] The organophosphorus-containing ligand for the catalyst system according to the present invention can be selected from any ligand known in hydroformylation. A number of suitable ligands are known to those skilled in the art from patent and technical literature, for example, mono- or biphosphite ligands. The organophosphorus-containing ligand preferably has the following general formula (II): R’-A-R”-A-R’’’ (II) (wherein R’, R’’ and R’’’ are each an organic group, provided that R’ and R’’’ are not the same, A is a -O-P(-O)2- group for each of the two crosslinks, and two of the three oxygen atoms -O- are each bonded to the group R’ and the group R’’’) There is a biphosphite structure represented by. The organic groups R’, R’’ and R’’’ preferably do not have a trialkoxysilane group at the end.

[0022] In a preferred embodiment, R’, R’’ and R’’’ in the compound of formula (VI) are preferably selected from a substituted or unsubstituted 1,1’-biphenyl group, a 1,1’-binaphthyl group and an orthophenyl group, particularly a substituted or unsubstituted 1,1’-biphenyl group, provided that R’ and R’’’ are not the same. More preferably, the substituted 1,1’-biphenyl group has an alkyl group and / or an alkoxy group, particularly a C1-C4 alkyl group, more preferably a tert-butyl and / or methyl group, and / or preferably a C1-C5 alkoxy group, more preferably a methoxy group, at the 3,3’-position and / or 5,5’-position of the 1,1’-biphenyl basic structure.

[0023] According to the present invention, the above-described catalyst system is present in a heterogeneous state on a carrier made of a porous ceramic material. The term "heterogeneous on the carrier" in the context of the present invention is understood to mean that the catalyst system is immobilized by a stabilizer to form a thin solid or liquid film on the inner surface and / or outer surface of the solid carrier material. This film may be solid at room temperature and liquid under the reaction conditions. More specifically, the inner surface (internal surface) of the solid carrier material includes the inner surface of the pores. As the concept of immobilization, there are both cases where the catalyst system and / or catalytically active species are dissolved in a solid or liquid film (film), and cases where the stabilizer acts as an adhesion promoter or the catalyst system is adsorbed on the surface but not chemically / covalently bonded to the surface. Therefore, according to the present invention, the catalyst system is dispersed on the surface and / or in the pores of the carrier, rather than in a reaction solution in the conventional sense where the catalyst is uniformly dissolved.

[0024] The carrier according to the present invention to which the catalyst system is applied is made of silicon carbide (SiC). The bed of the carrier is made of a silicon carbide (SiC) molded body, and the SiC molded body is composed of a bulk in which the ratio of pores having a pore diameter in the range of 10 nm to 1000 nm is 20 to 70% or 25 to 50% with respect to the total amount of its pores. The molded body may be in various shapes, such as a trilobal shape, a ring shape, a spherical shape, a cylindrical shape, etc. The size of the SiC molded body may be 0.1 mm to 50 mm. Such molded bodies are commercially available and can be manufactured, for example, by extrusion molding.

[0025] The application of the wash coat for manufacturing the carrier is disclosed in a previous application. This further step can be omitted in the present application. Therefore, the wash coat is not applied to the SiC molded body, and it is used without the wash coat. That is, there is no wash coat on the SiC molded body.

[0026] The catalyst system is applied to a support, i.e., a SiC molded body. For this purpose, first, a catalyst solution is prepared by mixing, especially at room temperature and ambient pressure, where the catalyst solution contains at least one organophosphorus-containing ligand, at least one metal precursor, for example, chlorides, oxides, carboxylates of each metal, at least one stabilizer, and at least one solvent. Optionally, an ionic liquid can be used in the preparation of the catalyst system, but the catalyst solution can also be prepared without using an ionic liquid. In particular, the catalyst solution is prepared in an inert environment, for example, inside a glove box. The "inert environment" in this case means an atmosphere that contains as little water and oxygen as possible.

[0027] The solvent can be selected from all solvent classes (protic, aprotic, polar or nonpolar). Prerequisites for the solvent are the solubility of the catalyst system (ligand, metal precursor, stabilizer, and optionally ionic liquid), and preferably the high boiling point formed in hydroformylation is also a prerequisite for the solvent. The solubility can be enhanced by heating during the immobilization process.

[0028] The solvent is preferably an aprotic and polar or aprotic polar solvent such as acetonitrile or ethyl acetate, or an aprotic nonpolar solvent such as THF or diethyl ether. Also, a chlorinated hydrocarbon such as dichloromethane or an aldehyde can be used as the solvent.

[0029] The catalyst solution thus produced is brought into contact with the support (optionally including a washcoat), for example, by impregnation (dip coating) or by filling a pressure vessel, for example, by direct injection into the reactor (in-situ impregnation). When applying the catalyst solution outside the reactor, after removing the solvent, the support needs to be reinstalled inside the reactor. Preferably, the catalyst solution is directly applied to the support together with the washcoat inside the reactor. This can avoid potentially time-consuming installation and removal steps, as well as potential contamination of the catalyst.

[0030] In the case of in-situ impregnation, the reactor can be purged with an inert gas, such as a noble gas, an alkane, or nitrogen, before filling. The purge can be carried out at 1 to 25 bar, preferably at a slight overpressure 20 to 90 mbar, more preferably 30 to 60 mbar higher than the standard pressure. Cooling the reactor before purging with the inert gas can prevent the solvent in the introduced catalyst solution from vaporizing immediately. However, if the boiling point of the solvent is higher than the temperature of the reactor, it is not necessary to cool the reactor.

[0031] The injection of the catalyst solution into the reactor can be carried out from a normal inlet or outlet, for example, using a pump. The liquid distributor and nozzle in the reactor can ensure the uniform distribution of the catalyst liquid and, in some cases, can control the existing pressure loss equipment and injection rate.

[0032] After applying the catalyst system, the solvent is separated. First, the catalyst solution is discharged from the outlet of the reactor. The solvent remaining in the reactor is vaporized by adjusting the pressure or raising the temperature. In other embodiments, the pressure can be adjusted while raising the temperature at the same time. Depending on the solvent, the temperature can be 20 to 150 °C. For some solvents, a high vacuum (10 -3 ~10 -7 mbar) can be set, but depending on the solvent and temperature, an overpressure of several mbar to several bar may also be acceptable.

[0033] The stabilizer is immobilized on a support together with a catalyst consisting of a transition metal, in particular cobalt or rhodium, and an organophosphorus-containing ligand. The catalyst system can be applied to the support either by direct injection into the reactor (in-situ impregnation) or outside the reactor. When applying the catalyst system outside the reactor, the support always needs to be transported in the absence of air, which can be achieved, for example, with a nitrogen countercurrent. In a preferred embodiment of the invention, the catalyst system is applied directly into the reactor, i.e., in-situ. After separating the solvent, the reactor can be immediately used to fill the feed mixture. This has the advantage that it does not require time-consuming installation and removal steps that would shut down the reactor for a long time. Furthermore, the size of the support is no longer restricted in that a suitable space of an inert environment can be utilized in a specific size. The size of the support can be freely selected according to the design of the reactor.

[0034] Once the catalyst system has been applied to the support and the solvent has been separated, the system, more specifically the reactor, can be started using a two-stage or multi-stage start-up procedure. I.e., it can be put into operation. Suitable start-up procedures are disclosed, for example, in European Patent Application No. 3632887.

[0035] From the reaction zone in which the hydroformylation according to the invention is carried out, a gaseous effluent containing at least a portion of the formed product aldehyde and at least a portion of the unreacted olefin is continuously removed. The gaseous effluent can be subjected to one or more physical separation steps, in which the gaseous effluent is separated into at least one phase rich in unreacted olefin and at least one phase rich in product aldehyde. The separation of substances can be carried out using known substance separation processes such as condensation, distillation, centrifugation, nanofiltration or some combination thereof, preferably condensation or distillation. In the case of multi-stage separation, the product aldehyde-rich phase formed during the first separation can be fed to a second separation, in particular an aldehyde separation downstream, where the product aldehyde is separated from other substances present in this phase, often generally alkanes and the reactant olefin. The olefin-rich phase can be returned to the hydroformylation process or, in the case of a multi-stage configuration, to one of the hydroformylation steps in order to hydroformylate the olefins contained therein to product aldehydes.

[0036] In addition to the above phases, during the separation of substances, a purge gas stream with at least a similar or identical composition to the olefin-rich phase can also be removed. The purge gas stream can be led to a second substance separation or aldehyde separation in order to separate the product aldehyde contained therein and remove impurities (e.g., nitrogen in synthesis gas) or inert substances (e.g., alkanes in the feed mixture) from the system. Impurities or inert substances can usually be removed, for example, at the top of a column, during the second separation of substances as volatile substances.

[0037] A further object of the present invention is also that the present invention relates to a plant comprising a reactor in which the process according to the present invention can be carried out and in particular in which the hydroformylation process according to the present invention is carried out. Furthermore, the plant can include a substance separation unit in which the gaseous effluent of the hydroformylation step is separated into at least one phase rich in unreacted olefin and at least one phase rich in product aldehyde, and the substance separation unit is arranged downstream of the hydroformylation according to the present invention. Downstream of the first substance separation unit, a second substance separation unit, in particular an aldehyde separation unit, may be present, in which the product aldehyde is separated.

[0038] Even without further explanation, it is considered that those skilled in the art can make the most of the above description. Therefore, the preferred embodiments and examples should be interpreted merely as descriptive disclosures and should in no way be construed as limiting disclosures. The present invention will be described in more detail below with reference to examples. Alternative embodiments of the present invention are available in a similar manner.

Examples

[0039] [Example 1] SiC extruded material SiC3-E2-HP commercially available from SICAT SARL was used as a carrier. Thereafter, this carrier was placed in a circular reactor sleeve with a diameter of 1 inch (about 2.54 cm) and a length of 20 cm, and glass beads of a similar size were filled above and below the pellets thereby. This carrier was contacted in situ (inside the reactor) with a catalyst solution containing Rh(acac)(CO)2, bisphos (ligand), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (stabilizer) and dichloromethane as a solvent. For this purpose, after flushing (purging) the reactor with nitrogen, the catalyst solution was introduced into the reactor with a slight overpressure. After extracting and evaporating the solvent from the reactor, hydroformylation was carried out. A hydrocarbon stream having the following composition was used as a feed mixture:

[0040]

Table 1

[0041] [Example 2] It was carried out in the same procedure as in Example 1. However, a commercially available SiC extruded material SiC4-E2-HP from SICAT SARL was used as the carrier. A hydrocarbon stream having the following composition was used as the feed mixture:

[0042]

Table 2

Claims

1. A process for hydroformylating C2-C8 olefins in a reaction zone using a heterogeneous catalyst system, the process comprising passing a gaseous feed mixture containing C2-C8 olefins together with synthesis gas over a carrier made of a porous ceramic material on which a hydroformylation catalyst system containing a metal of Group 8 or 9 of the periodic table, at least one organophosphorus-containing ligand, and a stabilizer is heterogeneously arranged, wherein, The bed of the carrier is made of a silicon carbide (SiC) molded body, and the SiC molded body has a ratio of pores with a diameter in the range of 10 nm to 1000 nm of 20 to 70% or 25 to 50% of the total amount of pores. process.

2. The process according to claim 1, wherein no wash coat is applied to the SiC molded article, and the article is used without the wash coat.

3. The organophosphorus-containing ligand of the hydroformylation catalyst system is given by the following general formula (II): R'-A-R''-A-R''' (II) (In the formula, R', R'' and R''' are each organic groups, however R' and R''' are not identical, and both A are bridging -O-P(-O)) ２ (It is a - group, and two of the three oxygen atoms -O- are bonded to groups R' and R''' respectively.) The process according to claim 1, as represented by the statement.

4. The stabilizer is given by the following formula (I) 【Chemistry 1】 The process according to claim 1, wherein the organic amine compound comprises at least one 2,2,6,6-tetramethylpiperidine unit.

5. The process according to claim 1, wherein the hydroformylation is carried out at a temperature in the range of 65 to 200°C, 75 to 175°C, or 85 to 150°C.

6. The process according to claim 1, wherein the pressure during hydroformylation is 35 bar or less, 30 bar or less, or 25 bar or less.

7. The process according to claim 1, wherein the hydroformylation catalyst system does not contain an ionic liquid.

8. The process according to claim 1, wherein a C4 olefin is used in the hydroformylation step.

9. The process according to claim 1, wherein the metal of group 8 or group 9 of the periodic table is rhodium.

10. The process according to claim 1, wherein the size of the SiC molded body is 0.1 mm to 50 mm.

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