Process for recovering rhodium from a hydroformylation process

Abstract

The present invention generally relates to a method for recovering rhodium from a catalyst purge stream from a C6 or higher olefin hydroformylation process. In one embodiment, the method comprises (a) treating a liquid purge stream containing a catalyst from the hydroformylation process with an oxidant in the presence of a separate liquid aqueous phase containing a halide-free acid at a temperature sufficient to achieve oxidation of a majority of the contained organophosphorus ligands, wherein the catalyst comprises a noble metal and an organophosphorus ligand, wherein the halide-free acid is a C1-C6 organic acid or phosphorous acid; (b) recovering the aqueous phase; (c) contacting the two phases by mixing the aqueous phase with a separate organic phase under a syngas atmosphere, wherein the separate organic phase comprises a water-insoluble hydrolyzable organophosphorus ligand and recycled olefins from the hydroformylation process; and (d) separating the organic phase to be recycled back to the hydroformylation process.

Description

Technical Field

[0001] The present invention relates to a method for recovering rhodium from a hydroformylation process, and in particular to a method for recovering rhodium from a hydroformylation process, wherein the hydroformylation process comprises producing at least one aldehyde in the presence of a catalyst in a reaction zone comprising C 6 or higher olefins, hydrogen and carbon monoxide, wherein the catalyst comprises rhodium and an organophosphorus ligand. Background Art

[0002] It is well known that continuous hydroformylation processes will slowly form relatively high boiling aldehyde-derived byproducts over time (see, e.g., U.S. Pat. Nos. 4,148,830 and 4,247,486). Because these "heavies" (as further defined below) are typically used as reaction solvents, they are initially allowed to accumulate during liquid recycle, but product separation conditions (e.g., temperature, pressure, stripping gas flow rate, etc.) must be adjusted to prevent their concentration from increasing beyond practical limits. Establishing the ratio of reactor effluent (feed) introduced into the separation zone relative to non-volatiles (tails) returned to the reaction zone while still maintaining the desired aldehyde production rate will ultimately determine the maximum concentration of heavies that the system can sustain. Once the heavies concentration limit is reached, they must be removed at a rate comparable to their formation rate to maintain the desired balance. A common method for removing heavies is volatilization; however, if the byproducts have a boiling point that is too high to be distilled overhead (e.g., derived from higher olefins), they may need to be removed from the system as a liquid purge stream (e.g., removing the separation zone liquid effluent) to extend catalyst life. The costs are associated with the wash liquid, including the recovery of rhodium from the wash liquid.

[0003] Hydroformylation catalysts comprising rhodium and a hydrolyzable organophosphorus ligand such as an organomonophosphite are capable of very high reaction rates (see, e.g., Rhodium Catalyzed Hydroformylation, van Leeuwen, Claver, Kluwer Academic Pub. (2000)). Such catalysts have industrial applicability because they can be used to increase productivity, or to efficiently hydroformylate internal olefins and / or branched internal olefins, which react more slowly than linear alpha-olefins.

[0004] Therefore, a number of processes have been developed to remove and recover rhodium from streams (such as liquid purge streams with heavies) in hydroformylation processes; examples include selective separation of phosphine using concentrated phosphoric acid (see, e.g., U.S. Pat. Nos. 4,242,284 and 4,710,587), using membrane or nanofiltration processes (see, e.g., U.S. Pat. Nos. 5,395,979 and 5,681,473), oxidation processes (see, e.g., U.S. Pat. Nos. 4,021,463, 4,196,096, 4,374,278, 4,400,547, 4,528,403, 4,605,780, and 5,290,743), etc. It would be desirable to have an alternative process for recovering rhodium from a hydroformylation process, particularly the hydroformylation of higher olefins, in which the introduction of components that interfere with the hydroformylation process is minimized. Summary of the invention

[0005] In some embodiments, the present invention advantageously provides methods that can allow for the recovery of rhodium from a liquid purge stream in a hydroformylation process using a reasonable number of process steps. In some embodiments, such methods can advantageously return a high percentage of rhodium in active form to the hydroformylation process for further use in hydroformylation, rather than sending it to a precious metal recovery operation. In some embodiments, the methods of the present invention can advantageously return active rhodium to the hydroformylation process in a manner that minimizes decomposition of the organophosphorus ligand used in the hydroformylation.

[0006] In one aspect, a method for recovering rhodium from a catalyst purge stream from a C6 or higher olefin hydroformylation process comprises:

[0007] (a) treating a catalyst-containing liquid purge stream from a hydroformylation process with an oxidizing agent in the presence of a separate liquid aqueous phase comprising a halide-free acid at a temperature sufficient to effect oxidation of a substantial portion of the contained organophosphorus ligands, wherein the halide-free acid is a C1-C6 organic acid or phosphorous acid;

[0008] (b) recovering the aqueous phase;

[0009] (c) contacting the aqueous phase with a separate organic phase by mixing the two phases under a synthesis gas atmosphere, wherein the separate organic phase comprises a water-insoluble, hydrolyzable organophosphorus ligand and a recycled olefin from a hydroformylation process; and

[0010] (d) separation of the organic phase to be recycled back into the hydroformylation process.

[0011] These and other embodiments are discussed in greater detail in the detailed description that follows. DETAILED DESCRIPTION

[0012] All references to the Periodic Table of the Elements and the various groups therein are to the version published in CRC Handbook of Chemistry and Physics, 72nd Edition (1991-1992) CRC Press, pp. 1-11.

[0013] Unless stated to the contrary or implicit from the context, all parts and percentages are based on weight and all test methods are current as of the application purpose of this application. For purposes of U.S. patent practice, the contents of any mentioned patent, patent application, or publication are incorporated by reference in their entirety (or their equivalent U.S. versions are so incorporated by reference), especially with respect to definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and common general knowledge in the art.

[0014] As used herein, "a", "an", "the", "at least one", and "one or more" are used interchangeably. The terms "comprising", "including", and variations thereof do not have a limiting meaning when these terms appear in the specification and claims. Thus, for example, an aqueous composition comprising "a" hydrophobic polymer particle can be interpreted to mean that the composition includes "one or more" hydrophobic polymer particles.

[0015] As used herein, the term "ppmw" means parts per million by weight.

[0016] For purposes of the present invention, the term "hydrocarbon" is intended to include all permitted compounds having at least one hydrogen and one carbon atom. Such permitted compounds may also have one or more heteroatoms. In a broad sense, permitted hydrocarbons include acyclic (with or without heteroatoms) and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic organic compounds, which may be substituted or unsubstituted.

[0017] As used herein, unless otherwise indicated, the term "substituted" is intended to include all permissible substituents of organic compounds. In a broad sense, permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. Exemplary substituents include, for example, alkyl, alkoxy, aryl, aryloxy, hydroxyalkyl, aminoalkyl, wherein the number of carbons can be 1 to 20 or more, preferably 1 to 12, and hydroxyl, halogen and amino. For suitable organic compounds, permissible substituents can be one or more and are identical or different. The present invention is not intended to be limited in any way by the permissible substituents of organic compounds.

[0018] As used herein, the term "hydroformylation" is intended to include, but is not limited to, all hydroformylation processes involving the conversion of one or more substituted or unsubstituted olefinic compounds or a reaction mixture comprising one or more substituted or unsubstituted olefinic compounds into one or more substituted or unsubstituted aldehydes or a reaction mixture comprising one or more substituted or unsubstituted aldehydes. The aldehydes may be asymmetric or non-asymmetric.

[0019] The terms "reaction fluid", "reaction medium" and "catalyst solution" are used interchangeably herein and may include, but are not limited to, a mixture comprising: (a) a metal-organophosphorus ligand complex catalyst, (b) free organophosphorus ligand, (c) an aldehyde product formed in the reaction, (d) unreacted reactants, (e) a solvent for the metal-organophosphorus ligand complex catalyst and the free organophosphorus ligand, and optionally (f) one or more soluble and / or suspended phosphoric acid compounds formed in the reaction. The reaction fluid may include, but are not limited to, (a) a fluid in a reaction zone, (b) a fluid stream on its way to a separation zone, (c) a fluid in a separation zone, (d) a recycle stream, (e) a fluid withdrawn from a reaction zone or a separation zone, (f) a fluid withdrawn after treatment with an acid removal system such as an extractor or other immiscible fluid contact system, (g) a treated or untreated fluid returned to a reaction zone or a separation zone, (h) a fluid in an external cooler, and (i) ligand decomposition products and components derived therefrom, such as oxides, sulfides, salts, oligomers, and the like.

[0020] As used herein, the term "spent catalyst" refers to a catalyst comprising a noble metal and an organophosphorus ligand that has degraded or become sufficiently contaminated that use is not economically feasible and requires replacement. In some embodiments, a spent catalyst is a catalyst having an activity less than 75% of its initial activity (reaction rate). In some embodiments, the activity of a spent catalyst is less than 50% of its initial activity (reaction rate). In a liquid purge operation, a portion of the catalyst is removed to allow fresh catalyst to be added to the remaining catalyst in the continued operation, but since the purge stream is not returned to the reactor, it is considered "spent catalyst."

[0021] As used herein, "spent catalyst fluid" and "catalyst-containing liquid purge stream" are used interchangeably and each refers to a fluid from a hydroformylation process that includes spent catalyst and may also include, but is not limited to, a mixture comprising: (a) a noble metal-organophosphorus ligand complex catalyst, (b) free organophosphorus ligand, (c) aldehyde products formed in the hydroformylation reaction, (d) unreacted reactants, (e) solvent for the metal-organophosphorus ligand complex catalyst and the free organophosphorus ligand, (f) free noble metal and / or clusters comprising noble metal, and optionally (g) one or more phosphoric acid compounds formed in the reaction (which may be homogeneous or heterogeneous). Additional contaminants may include aldehyde degradation products (e.g., carboxylic acids or alcohol and aldehyde condensation products), deactivated or poisoned catalysts, process fluids, water, pipeline flushes, etc. As used herein, the term "liquid purge stream" means a liquid stream in a hydroformylation process that exits the recycle process and is used to remove inerts, impurities, byproducts, ligand degradation materials, and other undesirable materials that may otherwise accumulate.

[0022] As used herein, the term "recycled olefins" includes a stream that has been recovered or derived from such a stream after a hydroformylation process, so that the contained olefins have passed through a hydroformylation process at least once. The stream is usually generated after a product-catalyst separation process, and is usually a part of a downstream purification of a crude aldehyde product. Alternatively, the material can be produced after further downstream refining of the alcohol obtained after aldehyde hydrogenation (recognizing that the stream at this time can have a very low olefin content). In any case, the "recycled olefins" stream may contain significant levels of aldehydes, hydrocarbons (e.g., hydrogenated olefins), alcohols, and other materials, but will preferably have less than 50% by weight of oxygenates, preferably less than 20% by weight of oxygenates, and most preferably less than 5% by weight of oxygenates, each based on the gross weight of the stream, wherein these oxygenates include at least one aldehyde, ester, and / or alcohol derived from the original olefin feed. In some embodiments, "recycled olefins" refers to a stream that has passed through a hydroformylation process at least once and has passed through a product-catalyst separation process at least once, and the total amount of aldehydes, esters, and / or alcohols in the recycled olefins is less than 5% by weight.

[0023] The "recycled olefin" stream exhibits a lower reactivity than the original olefin feed to the hydroformylation process, so that during step (c) of the recovery process described herein below (contacting the two phases by mixing the aqueous phase with a separate organic phase under a syngas atmosphere, wherein the separate organic phase comprises the water-insoluble hydrolyzable organophosphorus ligand and the recycled olefin from the hydroformylation process), the amount of aldehydes formed during syngas processing is minimized. The lower reactivity is generally due to the linear alpha olefin content (e.g., H 2 C=CH-CH 2-part) is reduced. Examples of these less reactive olefins are isomerized olefins (e.g., internal olefins) or branched olefins (e.g., H 2 C=C(Me)-CH 2 -), etc. The reactivity of olefins and olefin mixtures can be measured by a number of well-known techniques; for example, by determining the production rate under hydroformylation conditions, which can generally be expressed in units of gmol / L / hr (moles of aldehyde produced per liter of catalyst solution per hour), under a set of specified conditions, such as temperature, catalyst concentration, and synthesis gas partial pressure. Under normal conditions using C6 and higher olefins, the more reactive olefins are rapidly consumed, so that the unreacted olefins recovered are those that exhibit much lower reactivity and are therefore very suitable for use in the embodiments of the present invention.

[0024] The term "free ligand" refers to a ligand that is not complexed (or bound) to a metal, eg, a metal atom, of a complex catalyst.

[0025] A "hydrolyzable organophosphorus ligand" is a trivalent phosphorus P containing at least one PZ bond. (III) The ligand may be a monodentate hydrolyzable organophosphorus ligand. In some embodiments, the ligand may include a bidentate compound capable of forming a chelate complex with a noble metal and / or may contain a plurality of PZ moieties, such as polyphosphites, polyphosphoramidites, and mixed PZ moieties, such as phosphites-phosphoramidites, fluorophosphites-phosphites, etc. In some embodiments, a mixture of ligands may be used.

[0026] As used herein, the terms "heavy byproducts" and "heavies" are used interchangeably and refer to byproducts from a hydroformylation process that have a normal boiling point at least 25°C higher than the normal boiling point of the desired product (i.e., the desired aldehyde) of the hydroformylation process. Such materials are known to be formed in the hydroformylation process under normal operation by one or more side reactions, including, for example, by aldol condensation or ligand degradation. Non-limiting examples of heavies are described, for example, in U.S. Pat. No. 4,148,830.

[0027] As used herein, the term "dimer" refers to a heavy byproduct derived from two molecules of aldehyde. Likewise, the term "trimer" refers to a heavy byproduct derived from three molecules of aldehyde.

[0028] As used herein, the terms "isononanal" and "mixed C9 aldehydes" are used interchangeably and refer to a fluid composed of two or more aldehyde isomers, each of which contains nine carbon atoms. Illustrative examples of C9 aldehydes include n-nonanal, 2-methyloctanal, 3-methyloctanal, 4-methyloctanal, 5-methyloctanal, 6-methyloctanal, 7-methyloctanal, 2-ethylheptanal, 2-propylhexanal, 3-propylhexanal, 4,5-dimethylheptanal, 2,3,4-trimethylhexanal, 3-ethyl-4-methylhexanal, 2-ethyl-4-methylhexanal, 2-propyl-3-methylpentanal, 2,5-dimethylheptanal, 2,3-dimethylheptanal, and the like.

[0029] As used herein, the terms "separation zone" and "evaporator" are used interchangeably and refer to a product-catalyst separation device, such as a distillation device, in which the product aldehyde is volatilized, condensed and collected overhead, while the non-volatile concentrated effluent (tailings or evaporator tailings) containing the homogeneous catalyst is returned to one or more of the reactors. The separation zone temperature is typically higher than the hydroformylation reactor temperature and may optionally be operated under reduced pressure. In one embodiment, the evaporator is characterized by a flowing gas of varying composition that aids in product removal and optionally helps stabilize the catalyst ("stripping gas evaporator"). Other product-catalyst separation devices include membranes, phase separation and extraction methods. The nature of the product-catalyst separation device is not critical to the present invention.

[0030] As used herein, the terms "feed to tails" and "feed to tails ratio" are used interchangeably and refer to the mass of the reaction fluid entering the separation zone relative to the mass of the separation zone tails that exit the bottom of the separation zone and return to the hydroformylation reactor. "Feed to tails" is an indication of the rate at which volatiles, such as aldehyde product, are removed from the reaction fluid. For example, a "feed to tails" of 2 means that the weight of the reaction fluid entering the separation zone is twice as large as the weight of the concentrated effluent returned to the hydroformylation reactor.

[0031] Some embodiments of the present invention relate to methods for recovering rhodium in a hydroformylation process. Such rhodium recovery methods are particularly suitable for use in a hydroformylation process comprising producing at least one aldehyde in the presence of a catalyst in a reaction zone comprising C 6 to C 22 Olefins, hydrogen and carbon monoxide, wherein the catalyst comprises rhodium and an organophosphorus ligand.

[0032] In some embodiments, a method for recovering rhodium from a catalyst purge stream from a C6 or higher olefin hydroformylation process comprises:

[0033] (a) treating a catalyst-containing liquid purge stream from a hydroformylation process with an oxidizing agent in the presence of a separate liquid aqueous phase comprising a halide-free acid at a temperature sufficient to effect oxidation of a substantial portion of the contained organophosphorus ligands, wherein the halide-free acid is a C1-C6 organic acid or phosphorous acid;

[0034] (b) recovering the aqueous phase;

[0035] (c) contacting the aqueous phase with a separate organic phase by mixing the two phases under a synthesis gas atmosphere, wherein the separate organic phase comprises a water-insoluble, hydrolyzable organophosphorus ligand and a recycled olefin from a hydroformylation process; and

[0036] (d) separating the organic phase to be recycled back to the hydroformylation process. As used in step (a), "a majority" of the contained organophosphorus ligands means 50% by weight or more of the contained organophosphorus ligands in the liquid purge stream. For ligands having more than one phosphorus atom per molecule, "a majority" of the contained organophosphorus ligands means 50% by weight or more of all phosphorus atoms in the contained organophosphorus ligands in the liquid purge stream. Quantifying the concentration of organophosphorus ligands and oxidized organophosphorus ligands (e.g., organophosphates) in the liquid purge stream can be accomplished by analytical techniques known to those skilled in the art, such as phosphorus NMR and high performance liquid chromatography (HPLC). HPLC is generally preferred, and therefore is the technique used below to determine whether a majority of the contained organophosphorus ligands are oxidized.

[0037] In some embodiments, the noble metal is rhodium and the organophosphorus ligand is a tertiary organophosphorus ligand. In some embodiments, the organophosphorus ligand is a monophosphite. In some embodiments, the oxidant is oxygen, air, oxygen diluted in an inert gas, hydrogen peroxide, an alkyl peroxide, an aryl peroxide, a dialkyl peroxide, a diaryl peroxide, or a peroxyacid having less than 9 carbon atoms.

[0038] In some embodiments, the method further comprises, after recovering the aqueous phase in step (b), treating the remaining organic phase from step (a) with water or with an aqueous solution comprising a halide-free C1-C6 organic acid or phosphorous acid, or with an oxidizing agent in the presence of a separate liquid aqueous phase comprising a halide-free C1-C6 organic acid or phosphorous acid, recovering a second aqueous phase, and combining the second aqueous phase with the aqueous phase in step (b) before step (c).

[0039] In certain embodiments, the non-halide acid in step (a) is provided as an aqueous solution before treating the liquid cleaning stream, wherein in certain embodiments, the aqueous stream comprises at least 15 wt % of the non-halide acid, in certain embodiments, comprises at least 25 wt % of the non-halide acid, and in certain embodiments, comprises at least 40 wt % of the non-halide acid. In certain embodiments, a mixture of non-halide acid is provided. In certain embodiments, the non-halide acid in step (a) is a non-halide C1-C2 organic acid or phosphorous acid. In certain such embodiments, a mixture of non-halide C1-C2 organic acid or phosphorous acid is used. The example of the non-halide C1-C2 organic acid that can be used in some embodiments of the present invention includes formic acid, acetic acid, glycolic acid and oxalic acid, wherein acetic acid is particularly useful.

[0040] In some embodiments, the recycle olefin used in step (c) comes from a hydroformylation process different from a liquid purge stream containing a catalyst. In some embodiments, the recycle olefin used in step (c) comes from a hydroformylation process identical to a liquid purge stream containing a catalyst. In some embodiments, the recycle olefin is C6 or higher and has a lower hydroformylation activity than the olefin feed used in the hydroformylation process generating a liquid purge stream containing a catalyst. In some embodiments, the recycle olefin is C6 or higher and has a higher average branching degree than the olefin feed used in the hydroformylation process generating a liquid purge stream containing a catalyst. Without being bound by any particular theory, since the oxidation process can generate organic acids derived from product aldehydes or heavies, it is believed that adding recycle olefins can help mitigate the effects of high molecular weight acids that tend to form surfactants and emulsions. This can also reduce the amount of halide-free C1-C2 organic acids or phosphorous acid present in the organic phase, which can be used to use the organic phase for downstream operations, and minimize the loss of halide-free C1-C2 organic acids or phosphorous acid.

[0041] In some embodiments, the method further comprises washing the organic phase from step (d) with an aqueous wash liquid before sending the organic phase to the hydroformylation process. In some embodiments, the aqueous wash liquid comprises a water-soluble amine. In some embodiments, the water-soluble amine has the following structure:

[0042]

[0043] Where R 1 , R 2 and R 3 are each independently alkyl and ethoxylate, and wherein R 1 , R 2 and R 3 In some embodiments, no more than one of R 1 , R 2 and R3 Each is an ethoxylate. In some embodiments, the concentration of the amine is 1.5 to 20% by weight, based on the total weight of the aqueous wash, and the amount of the amine-containing solution is 2.5 to 50% by weight of the organic phase. In some embodiments, the water-soluble amine is triethanolamine. In some embodiments, a buffer salt may be used instead of a water-soluble amine; such buffer salts are described in U.S. Patent No. 5,741,944 and PCT Publication No. WO2013184350. In some embodiments, if the aqueous wash does not include a water-soluble amine or a buffer salt, the decanted bottom water layer may be recycled as part of the initial liquid aqueous phase used in step (a).

[0044] In some embodiments, the method further comprises bubbling the aqueous phase with an inert gas or synthesis gas after recovering the aqueous phase in step (b) and before introducing the water-insoluble hydrolyzable organophosphorus ligand in step (c). In some embodiments, the inert gas comprises nitrogen, argon, helium or methane.

[0045] In some embodiments, the method of the present invention further comprises returning the organic phase comprising the noble metal-organophosphorus complex to the reaction zone in the hydroformylation process. In some embodiments, the method of the present invention further comprises providing the organic phase comprising the noble metal-organophosphorus complex to the hydroformylation process prior to the product-catalyst separation zone so that any residual halide-free C1-C6 organic acid or phosphorous acid can be removed with the product before the material is returned to the reaction zone. In some embodiments, the method of the present invention further comprises providing the organic phase comprising the noble metal-organophosphorus complex to the hydroformylation process prior to entering the reaction zone prior to or at an aqueous extractor as described in U.S. Pat. No. 5,741,944.

[0046] The process requires hydrogen and carbon monoxide. These can be obtained from any suitable source, including petroleum cracking and refining operations. Synthesis gas mixtures are commonly used as a source of hydrogen and CO.

[0047] As used herein, “syngas” refers to a gas containing varying amounts of CO and H. 2 Production methods are well known and include, for example: (1) steam reforming and partial oxidation of natural gas or liquid hydrocarbons, and (2) gasification of coal and / or biomass. Hydrogen and CO are generally the main components of syngas, but syngas may contain carbon dioxide and inert gases such as CH 4 、N 2 and Ar.H 2The molar ratio of H to CO varies widely but is generally 1:100 to 100:1, preferably 1:10 to 10:1. Synthesis gas is commercially available and is often used as a fuel source or as an intermediate in the production of other chemicals. For chemical production, the most preferred H 2 The molar ratio of HO:CO is between 3:1 and 1:3, and for most hydroformylation applications is typically between about 1:2 and 2:1.

[0048] The olefin starting material reactant that can be used in the hydroformylation method of the present invention includes optically active (prochiral and chiral) and non-optically active (achiral) olefinic unsaturated compounds containing 6 to 22, preferably 8 to 22, and more preferably 8 to 20 carbon atoms. Such olefinic unsaturated compounds can be substituted or unsubstituted, terminal or internally unsaturated, straight chain, branched chain or cyclic. Olefin mixtures can be used, such as olefin mixtures obtained by oligomerization of propylene, butene, isobutylene, etc. (such as so-called dimerization, trimerization or tetramerization butene, etc., as disclosed in, for example, U.S. Patents 4,518,809 and 4,528,403). In addition, such olefin compounds can further contain one or more additional olefinic unsaturated groups, and if necessary, a mixture of two or more different olefinic unsaturated compounds can be used as a starting hydroformylation material. For example, commercially available α-olefins containing 8 or more carbon atoms can contain a small amount of corresponding internal olefins and / or their corresponding saturated hydrocarbons, and such commercially available olefins do not have to be purified from them before hydroformylation. Exemplary mixtures of olefin starting materials useful for the hydroformylation reaction include, for example, mixed butene dimers and trimers. In addition, such olefinically unsaturated compounds and the corresponding aldehyde products derived therefrom may also contain one or more groups or substituents that do not unduly adversely affect the hydroformylation process or the process of the present invention, as described, for example, in U.S. Pat. Nos. 3,527,809, 4,769,498, and the like.

[0049] Embodiments of the present invention are particularly useful for producing non-optically active aldehydes by hydroformylating achiral alpha-olefins containing 6 to 22, preferably 8 to 20 carbon atoms and achiral internal olefins containing 8 to 20 carbon atoms, and starting material mixtures of such alpha-olefins and internal olefins.

[0050] Exemplary alpha and internal olefins include, for example, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 2-heptene, 2-octene, propylene dimer, propylene trimer, propylene tetramer, 2-ethyl-1-hexene, and the like, including mixtures thereof.

[0051] Solvents are advantageously used in the hydroformylation process. Any suitable solvent that does not excessively interfere with the hydroformylation process may be used. For example, suitable solvents for rhodium-catalyzed hydroformylation include, for example, those disclosed in U.S. Pat. Nos. 3,527,809; 4,148,830; 5,312,996; and 5,929,289. Non-limiting examples of suitable solvents include saturated hydrocarbons (alkanes), aromatic hydrocarbons, water, ethers, polyethers, alkylated polyethers, aldehydes, ketones, nitriles, alcohols, esters, and aldehyde condensation products. Specific examples of solvents include: tetraglyme, pentane, cyclohexane, heptane, benzene, xylene, toluene, diethyl ether, tetrahydrofuran, butyraldehyde, and benzonitrile. The organic solvent may also contain dissolved water up to the saturation limit. Exemplary solvents that can be used to produce the aldehyde include ketones (e.g., acetone and methyl ethyl ketone), esters (e.g., ethyl acetate, di-2-ethylhexyl phthalate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), hydrocarbons (e.g., toluene), nitrohydrocarbons (e.g., nitrobenzene), ethers (e.g., tetrahydrofuran (THF)), and sulfolane. In rhodium-catalyzed hydroformylation, it may be desirable to use as the primary solvent an aldehyde compound corresponding to the aldehyde product and / or higher boiling aldehyde liquid condensation byproducts that are desired to be produced, e.g., as may be produced in situ during the performance of the hydroformylation process, as described, e.g., in U.S. Pat. Nos. 4,148,830 and 4,247,486. In practice, while any suitable solvent may be used at the start-up of a continuous process if desired, due to the nature of a continuous process, the primary solvent typically ends up containing the aldehyde product and higher boiling aldehyde liquid condensation byproducts (heavies). The amount of solvent is not particularly critical and need only be sufficient to provide the desired amount of transition metal concentration to the reaction medium. Typically, the amount of solvent is in the range of about 5 wt % to about 95 wt % based on the total weight of the reaction fluid. Mixtures of two or more solvents may also be used.

[0052] Although the hydroformylation reaction includes a solvent as described in the preceding paragraph, other solvents may be used in the process of the present invention.

[0053] Before or during the treatment with the oxidant described in step (a) of the present invention, additional solvents may optionally be added, especially if the purge stream is viscous. In such embodiments, these solvents should be of low polarity, such as C6 or higher olefin feeds, recycled olefin streams, hydrocarbons (e.g., hexane, heptane), aromatic hydrocarbons (e.g., toluene, xylene), etc. Preferably, no oxygen-containing, halogen-containing or nitrogen-containing solvents are added in this step.

[0054] The solvent used in step (d) of the present invention is different from the solvent used in the hydroformylation process and is referred to herein as the "recovery solvent". The recovery solvent comprises at least 50% of the recycled olefin as defined herein. Preferably, the recovery solvent comprises at least 70% and most preferably greater than 90% of the recycled olefin with the added hydrolyzable organophosphorus ligand. Other solvents such as those used in the hydroformylation process (described above) and / or fresh olefin feed may also be used as part of the recovery solvent.

[0055] Catalysts that can be used for the hydroformylation process include catalytic metals or noble metals. The noble metal can include metals from Groups 8, 9, and 10 selected from rhodium (Rh), cobalt (Co), iridium (Ir), ruthenium (Ru), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt), osmium (Os), and mixtures thereof, preferably rhodium, cobalt, iridium, and ruthenium, more preferably rhodium, cobalt, and ruthenium, particularly rhodium. The initial active metal can be delivered to the hydroformylation reaction system as a catalyst precursor or as an activated catalyst, as described in U.S. Patent No. 6,700,021. Embodiments of the present invention are particularly suitable for recovering rhodium, such that in some embodiments, the catalyst or noble metal is rhodium.

[0056] The number of coordination sites available on such metals is well known in the art. Thus, the catalytic species which may comprise a complex catalyst mixture may comprise monomers, dimers or higher nuclear forms which are preferably characterized in that each metal molecule (eg rhodium) is complexed with at least one organophosphorus-containing molecule.

[0057] Catalysts and methods for their preparation are well known in the art and include those disclosed in the above-mentioned patents. Typically, such catalysts consist essentially of a metal in complex combination with an organophosphorus ligand. It is believed that carbon monoxide is also present and complexed with the metal in the active material. The active material may also contain hydrogen directly bonded to the metal.

[0058] The organophosphorus ligands that are allowed to constitute the metal-organophosphorus ligand complex and the free organophosphorus ligands include mono-, di- and tri-organophosphites. Other organophosphorus ligands described above may also be used. If desired, a mixture of such ligands may be used in the metal-organophosphorus ligand complex catalyst and / or the free ligands, and such mixtures may be the same or different. The present invention is not intended to be limited to the initial organophosphorus ligand or its mixture that is allowed in any way. It should be noted that the successful practice of the present invention does not depend on and is not based on the exact structure of the initial metal-organophosphorus ligand complex material, which may exist in its mononuclear, binuclear and / or higher nuclear form. In fact, the exact structure is unknown. Although it is not desired to be bound by any theory or mechanism, it seems that the catalytic material may be composed of a metal complexed combination of an organophosphorus ligand and carbon monoxide and / or hydrogen in its simplest form. During the oxidation step (a), the organophosphorus ligand will be converted into its oxide and removed from the metal-organophosphorus ligand complex. Therefore, the nature of the initial organophosphorus ligands is not critical to the present invention since they are destroyed in step (a).

[0059] In some embodiments of the process of the present invention, the oxidation conditions in step (a) are selected to achieve substantial oxidation and preferably complete oxidation of the organophosphorus ligands present, while minimizing oxidation of the residual aldehydes present. The nature of the oxidant and organophosphorus ligand, the reaction time, and the reaction temperature will affect the rate and extent of oxidation of the organophosphorus ligand. Some guidance in the selective oxidation of organophosphorus ligands is given, for example, in U.S. Pat. No. 4,605,780. The progress of the oxidation can be analyzed by various conventional analytical techniques, such as high pressure liquid chromatography, gas chromatography or 31 P NMR is easily monitored. Excessive oxidation conditions should be avoided to minimize the oxidation of residual aldehyde products contained in the organic phase to their corresponding carboxylic acids. The amount of organic acid formed can also be monitored by conventional means, such as gas chromatography.

[0060] In certain embodiments, the mixture should be fully mixed in the oxidation process of step (a) so that the released precious metal can be transferred to the aqueous phase from the organic phase. However, it is important that the obtained phase is easy to separate to promote the recovery of the aqueous phase. Therefore, it is desirable to minimize the polarity of the organic phase by minimizing the amount of polar organic compounds (e.g., oxygen, nitrogen and halogen-containing organic compounds). Minimizing the content of aldehydes and higher acids (C6 and above) in the organic phase is important for embodiments of the present invention. This can be achieved by, for example, removing as much as possible aldehyde products before the oxidation in step (a) using a product-catalyst separation unit. If another solvent is added to step (a) to reduce viscosity, the solvent should generally be selected to include a minimum amount of oxygen, nitrogen and halogen-containing organic compounds.

[0061] The hydrolyzable organophosphorus ligand added in step (c) is preferably insoluble in water (in some embodiments, no more than 0.1 wt % in water, in some embodiments no more than 0.01 wt % in water, and preferably no more than 0.001 wt % in water). The resulting catalyst solution in the organic phase can then be added to a hydroformylation process with a different ligand (including a mixture of hydrolyzable and non-hydrolyzable ligands). The ligand added in step (c) is preferably the ligand in the original hydroformylation process from which the initial purge stream was generated, but the recovered catalyst solution can be used in a different hydroformylation process unit.

[0062] The term "complex" as used herein refers to a coordination compound formed by the combination of one or more electron-rich molecules or atoms capable of existing independently and one or more electron-poor molecules or atoms also capable of existing independently. Carbon monoxide, which is appropriately classified as a ligand, may also be present and coordinated to the metal. The final composition of the complex catalyst may also contain additional ligands, such as hydrogen or anions that satisfy the coordination sites or nuclear charge of the metal. Exemplary additional ligands include, for example, alkyl, aryl, substituted aryl, acyl, CN, (R) 2 PO and RP(O)(OH)O (wherein each R is the same or different and is a substituted or unsubstituted hydrocarbon group, such as an alkyl or aryl group), acetate, acetylacetonate, SO 4 PF 4 PF 6 、NO 2 、NO 3 , CH 3 , CH 2 =CHCH 2 , CH 3 CH=CHCH 2 , C 6 H 5 CN, CH 3 CN、NH 3 , pyridine, (C 2 H 5 ) 3 N, monoolefins, diolefins and triolefins, tetrahydrofuran, etc. The complex material preferably does not contain any additional organic ligands or anions that may poison the catalyst or have an adverse effect on catalyst performance. In the hydroformylation reaction catalyzed by the metal-organophosphorus ligand complex, it is preferred that the active catalyst does not contain halogens and sulfur directly bonded to the metal, but this may not be absolutely necessary.

[0063] Organophosphorus compounds that can serve as ligands and / or free ligands for metal-organophosphorus ligand complex catalysts can be of achiral (optically inactive) or chiral (optically active) type and are well known in the art.Achiral organophosphorus ligands are preferred.

[0064] Such organophosphorus ligands and / or methods for their preparation are well known in the art and include, for example, organophosphite ligands. As used herein, a "monoorganophosphite ligand" is a compound containing a single phosphorus atom bonded to three oxygen atoms; each of the three oxygen atoms is additionally bonded to a carbon moiety. Illustrative examples include, but are not limited to, monoorganophosphites, diorganophosphites, and triorganophosphite compounds, examples of which include: tris(2,4-di-tert-butylphenyl)phosphite, 4,8-di-tert-butyl-6-(2-(tert-butyl)-4-methoxyphenyl)-2,10-dimethoxydibenzo[d,f][1,3,2]dioxaphosphocyclopentene, and the like.

[0065] Representative monoorganophosphites may include those having the formula:

[0066]

[0067] Where R 10 The term "phosphite" refers to a substituted or unsubstituted trivalent hydrocarbon radical containing 4 to 40 or more carbon atoms, such as trivalent acyclic and trivalent cyclic radicals, for example trivalent alkylene radicals, such as those derived from 1,2,2-trimethylolpropane, etc., or trivalent cycloalkylene radicals, such as those derived from 1,3,5-trihydroxycyclohexane, etc. A more detailed description of such monoorganophosphites can be found, for example, in US 4,567,306.

[0068] Representative diorganophosphites can include those having the formula:

[0069]

[0070] Where R 20 represents a substituted or unsubstituted divalent hydrocarbon group containing 4 to 40 or more carbon atoms, and W represents a substituted or unsubstituted monovalent hydrocarbon group containing 1 to 36 or more carbon atoms.

[0071] Representative substituted and unsubstituted monovalent hydrocarbon groups represented by W in the above formula (II) include alkyl groups and aryl groups, while R 20 Representative substituted and unsubstituted divalent hydrocarbon groups include divalent acyclic groups and divalent aromatic groups. Exemplary divalent acyclic groups include, for example, alkylene, alkylene-oxy-alkylene, alkylene-S-alkylene, cycloalkylene, and alkylene-NR 24 -alkylene, where R 24is hydrogen or a substituted or unsubstituted monovalent hydrocarbon group, such as an alkyl group having 1 to 4 carbon atoms. More preferred divalent acyclic groups are divalent alkylene groups, such as those more fully disclosed in U.S. Pat. Nos. 3,415,906 and 4,567,302. Exemplary divalent aromatic groups include, for example, arylene, biarylene, arylene-alkylene, arylene-alkylene-arylene, arylene-oxy-arylene, arylene-NR 24 -arylene (where R 24 As defined above), arylene-S-arylene and arylene-S-alkylene, etc. More preferably, R 20 is a divalent aromatic group as more fully disclosed in, for example, U.S. Patents 4,599,206, 4,717,775, and 4,835,299 and PCT Publication WO2016087301, among others.

[0072] A more preferred class of diorganophosphites is represented by those of the formula:

[0073]

[0074] wherein W is as defined above, each Ar is the same or different and represents a substituted or unsubstituted aryl group, each y is the same or different and has a value of 0 or 1, and Q represents a group selected from -C(R 35 ) 2 -、-O-、-S-、-NR 36 -、Si(R 37 ) 2 and -CO-, wherein each R 35 are the same or different and represent hydrogen, alkyl, phenyl, tolyl and anisyl having 1 to 12 carbon atoms, R 36 As defined above, each R 37 are the same or different and represent hydrogen or a methyl group, and m has a value of 0 or 1. Such diorganophosphites are described in more detail, for example, in U.S. Patents 4,599,206, 4,717,775, and 4,835,299 and PCT Publication WO2016087301.

[0075] Representative triorganophosphites can include those having the formula:

[0076]

[0077] Each R 46The same or different and substituted or unsubstituted monovalent hydrocarbon groups, such as alkyl, cycloalkyl, aryl, alkaryl and aralkyl groups, may contain from 1 to 24 carbon atoms. Exemplary triorganophosphites include, for example, trialkyl phosphites, dialkylaryl phosphites, alkyldiaryl phosphites, triaryl phosphites, and the like, such as trimethyl phosphite, triethyl phosphite, diethylbutyl phosphite, tri-n-propyl phosphite, tri-n-butyl phosphite, tri-2-ethylhexyl phosphite, tri-n-octyl phosphite, tri-n-dodecyl phosphite, dimethylphenyl phosphite, diethylphenyl phosphite, methyldiphenyl phosphite, ethyldiphenyl phosphite, triphenyl phosphite, trinaphthyl phosphite, bis(3- hydroxyphenyl) ... The preferred triorganophosphite is tris(2,4-di-tert-butylphenyl) phosphite. Such triorganophosphites are described in more detail, for example, in U.S. Patents 3,527,809 and 4,717,775 and U.S. Publication No. US20150336093.

[0078] If desired, make-up or additional organophosphorus ligand may be supplied to the reaction medium of the hydroformylation process at any time and in any suitable manner, for example, to maintain a predetermined level of free ligand in the reaction medium.

[0079] The use of aqueous buffer solutions to prevent and / or reduce the hydrolytic degradation of organophosphorus ligands and the inactivation of metal-organophosphorus ligand complexes is disclosed in U.S. Patent No. 5,741,942. The aqueous buffer used in US 5,741,944 is generally a salt of a weak acid or base, but is generally a weak acid 1 or 2 group metal (Na, K, Ca, etc.) salt. In some cases where amines are used, when they neutralize and remove at least some amount of phosphate compounds from the reaction fluid, they generate ionic salts, such as ammonium salts. The aqueous buffer solution that can be used in the present invention can include any suitable buffer mixture containing oxoacid salts, and its properties and proportions in the mixture make their aqueous solution pH 3 to 9, preferably 4 to 8, more preferably 4.5 to 7.5. In this article, a suitable buffer system can include anions selected from phosphate, carbonate, citrate, maleate, fumarate and borate compounds and a mixture of cations selected from ammonium and alkali metals such as sodium, potassium, etc. Such buffer systems and / or their preparation methods are well known in the art. It is preferred to use a buffered extractor, particularly in the stream with recovered rhodium, to remove acids or other impurities before being introduced back into the reaction system.

[0080] The hydroformylation product may be asymmetric, non-asymmetric or a combination thereof, with the preferred product being non-asymmetric. The process may be conducted in any batch, continuous or semi-continuous manner and may involve any desired catalyst liquid and / or gas recycle operation.

[0081] The recycling procedure generally involves continuously or intermittently withdrawing a portion of the liquid reaction medium containing the catalyst and the aldehyde product from the hydroformylation reactor (i.e., the reaction zone) and recovering the aldehyde product therefrom by using a composite membrane (as disclosed in U.S. Pat. Nos. 5,430,194 and 5,681,473) or by distillation (e.g., evaporative separation) in a separate distillation zone at normal, reduced or elevated pressure (as the case may be) in one or more stages. The unvolatized metal catalyst containing the residue is recycled to the reaction zone as disclosed, for example, in U.S. Pat. No. 5,288,918. The condensation of the volatile materials and their separation and further recovery (e.g., by further distillation) may be carried out in any conventional manner, the crude aldehyde product may be passed for further purification and isomer separation, if desired, and any recovered reactants (e.g., olefin starting materials and synthesis gas) may be recycled to the hydroformylation process (reaction zone or reactor) in any desired manner. The recovered metal catalyst-containing raffinate of such membrane separation or the recovered non-volatile metal catalyst-containing residue of such evaporative separation may be recycled to the hydroformylation process (reaction zone or reactor) in any desired conventional manner.

[0082] In addition to the other components discussed herein, the hydroformylation reaction mixture compositions that can be used herein can and usually will contain small amounts of additional ingredients, such as those that have been intentionally used in the hydroformylation process or formed in situ during the performance of the process. Examples of such ingredients that may also be present include unreacted olefin starting materials, carbon monoxide and hydrogen, and in situ formed products, such as saturated hydrocarbons and / or unreacted isomerized olefins corresponding to the olefin starting materials, ligand degradation compounds, and high boiling liquid aldehyde condensation byproducts, such as polymer catalyst stabilizers described in U.S. Pat. No. 4,774,361 and PCT Publication No. WO2019 / 112866, and other inert co-solvent materials or hydrocarbon additives (if used).

[0083] The reaction conditions of the hydroformylation method covered by the embodiments of the present invention may include any suitable hydroformylation conditions used to date to produce optically active and / or non-optically active aldehydes. For example, the total gas pressure of hydrogen, carbon monoxide and olefin starting compounds of the hydroformylation method can be in the range of 1 to 69,000 kPa. However, it is generally preferred that the method is operated at a total gas pressure of hydrogen, carbon monoxide and olefin starting compounds less than 14,000 kPa, more preferably less than 3,400 kPa. The minimum total pressure is mainly limited by the amount of reactants required to obtain the desired reaction rate. More specifically, the carbon monoxide partial pressure of the hydroformylation method of the present invention is preferably 1 to 6,900 kPa, more preferably 21 to 5,500 kPa, and the hydrogen partial pressure is preferably 34 to 3,400 kPa, more preferably 69 to 2,100 kPa. In general, the H of gaseous hydrogen and carbon monoxide in the reaction zone is preferably 1 to 6,900 kPa, more preferably 21 to 5,500 kPa. 2 The molar ratio of hydrogen to carbon monoxide may range from 1:10 to 100:1 or more, more preferably the molar ratio of hydrogen to carbon monoxide is from 1:10 to 10:1.

[0084] In general, the hydroformylation process can be carried out at any operable reaction temperature. Advantageously, the hydroformylation process is carried out at a reaction temperature of -25°C to 200°C. Typically, a hydroformylation reaction temperature of 50°C to 120°C is preferred for all types of olefin starting materials. The hydroformylation reaction conditions employed will be governed by the type of aldehyde product desired.

[0085] The hydroformylation process of the present invention can be carried out using one or more suitable reactors, such as fixed bed reactors, fluidized bed reactors, tubular reactors, venturi reactors, bubble column reactors, continuous stirred tank reactors (CSTR) or slurry reactors. The optimal size and shape of the reactor will depend on the type of reactor used. As further discussed below, the hydroformylation process may include one or more reaction zones, one or more separation zones and one or more buffer treatment zones. The reaction zone used in the present invention can be a single container or can include two or more discrete containers. The separation zone used in the present invention can be a single container or can include two or more discrete containers. The buffer treatment zone used in the present invention can be a single container or can include two or more discrete containers. The reaction zone and separation zone used herein can be present in the same container or in different containers. For example, reactive separation techniques such as reactive distillation, reactive membrane separation, etc. can occur in the reaction zone.

[0086] The hydroformylation process of the present invention may be carried out in a batch or continuous manner, with recycling of unconsumed starting materials if desired. The hydroformylation reaction may be carried out in a single reaction zone or in a plurality of reaction zones connected in series or in parallel, or it may be carried out in an elongated tubular zone or a series of such reaction zones, either batchwise or continuously. The materials of construction used should be substantially inert to the starting materials during the reaction, and the equipment should be constructed to withstand the reaction temperatures and pressures.

[0087] The hydroformylation process of the present invention may be carried out in one or more steps or stages. The exact number of reaction steps or stages will be governed by the best compromise between capital cost and achieving high catalyst selectivity, activity, lifetime and ease of operation, as well as the inherent reactivity of the starting materials in question and the stability of the starting materials and the desired reaction products to the reaction conditions.

[0088] In one embodiment, the hydroformylation can be carried out in a multi-stage reactor, as described, for example, in U.S. Patent No. 5,728,893. Such a multi-stage reactor can be designed with internal physical barriers that produce more than one theoretical reaction stage in each container. In fact, it is similar to having multiple reactors within a single continuous stirred tank reactor vessel. Multiple reaction stages within a single container is a cost-effective way to use the reactor vessel volume. This significantly reduces the number of containers required to achieve the same result. Fewer containers reduce the total capital required and the maintenance issues for separate containers and agitators.

[0089] As described above, it is generally preferred to carry out the hydroformylation process of the present invention in a continuous manner. In general, continuous hydroformylation processes are well known in the art and may involve: (a) hydroformylating an olefin starting material with carbon monoxide and hydrogen in a liquid homogeneous reaction mixture comprising a solvent, a metal-organophosphorus ligand complex catalyst, and free organophosphorus ligands; (b) maintaining reaction temperature and pressure conditions that are favorable for the hydroformylation of the olefin starting material; (c) when these reactants are exhausted, supplying a supplementary amount of olefin starting material, carbon monoxide, and hydrogen to the reaction medium; and (d) recovering the desired aldehyde hydroformylation product in any desired manner. The continuous process may be carried out in a single pass mode, i.e., wherein a vaporous mixture comprising unreacted olefinic starting material and evaporated aldehyde product is removed from the liquid reaction mixture, thereby recovering the aldehyde product and supplying supplementary olefinic starting material, carbon monoxide, and hydrogen to the liquid reaction medium for the next single pass without recycling unreacted olefinic starting material. Such recycling procedures are well known in the art and may involve liquid recycling of the metal-organophosphorus complex catalyst fluid separated from the desired aldehyde reaction product, as disclosed, for example, in U.S. Pat. No. 4,148,830; or gas recycling procedures, as disclosed, for example, in U.S. Pat. No. 4,247,486; and combinations of liquid and gas recycling procedures when necessary. The most preferred hydroformylation process of the present invention comprises a continuous liquid catalyst circulation process. Suitable liquid catalyst recycling procedures are disclosed, for example, in U.S. Pat. Nos. 4,668,651; 4,774,361; 5,102,505 and 5,110,990.

[0090] In one embodiment of the invention, the aldehyde product mixture can be separated from the other components of the crude reaction mixture, wherein the aldehyde mixture is prepared by any suitable method. Suitable separation methods include, for example, solvent extraction, crystallization, distillation, evaporation, scraped film evaporation, falling film evaporation, phase separation, filtration, etc. or any combination thereof. It may be necessary to remove the aldehyde product from the crude reaction mixture because they are formed by using a trapping agent, as described in PCT Publication No. WO 88 / 08835. One method of separating the aldehyde mixture from the other components of the crude reaction mixture is by membrane separation. Such membrane separation can be achieved as described in U.S. Patents 5,430,194 and 5,681,473.

[0091] As described above, at the end of (or during) the process of the present invention, the desired aldehyde can be recovered from the reaction mixture used in the process of the present invention. For example, the recovery techniques disclosed in U.S. Pat. Nos. 4,148,830 and 4,247,486 can be used. For example, in a continuous liquid catalyst recycle process, a portion of the liquid reaction mixture containing the aldehyde product, catalyst, etc. removed from the reaction zone (i.e., the reaction fluid) can be transferred to a separation zone (e.g., an evaporator / separator), where the desired aldehyde product can be separated from the liquid reaction fluid via distillation at normal, reduced or elevated pressure in one or more stages, condensed and collected in a product receiver, and further purified as needed. The remaining liquid reaction mixture containing the unvolatile catalyst (usually referred to as "evaporator tails" when an evaporator is used) can then be recycled back to the reactor, and any other volatile materials (e.g., unreacted olefins) can be separated from the condensed aldehyde product together with any hydrogen and carbon monoxide dissolved in the liquid reaction, such as by distillation in any conventional manner. Generally, it is preferred to separate the desired aldehyde from the catalyst-containing reaction mixture under reduced pressure and low temperature to avoid possible degradation of the organophosphorus ligand and reaction products.

[0092] More specifically, the distillation and separation of the desired aldehyde product from the reaction fluid containing the metal-organophosphorus complex catalyst can be carried out at any suitable temperature desired. Generally, it is preferred that such distillation be carried out at a relatively low temperature, such as less than 150° C., more preferably at a temperature of 50° C. to 140° C. It is also generally preferred that such aldehyde distillation be carried out under reduced pressure, such as when low boiling aldehydes (such as C 4 To C 6 ), the total gas pressure is significantly lower than that employed during hydroformylation, or when high-boiling aldehydes (e.g. C 7 or greater), is conducted under vacuum. For example, it is common practice to subject the liquid reaction product medium removed from the hydroformylation reactor to reduced pressure in order to volatilize a substantial portion of the unreacted gases dissolved in the liquid medium, which now contains a much lower concentration of synthesis gas than that present in the reaction medium, to a distillation zone, such as an evaporator / separator, where the desired aldehyde product is distilled. In general, distillation pressures ranging from vacuum pressures to total gas pressures of up to 340 kPa should be sufficient for most purposes.

[0093] It has been found that as the molecular weight of the aldehyde increases, the removal of the aldehyde condensation byproducts ("heavies") becomes more difficult, especially with distillation processes. The elevated temperatures required to vaporize these high molecular weight materials tend to generate even more heavies, so that a practical limit is reached when these heavies accumulate to unacceptable levels. This process is often catalyst life limited unless catalyst washing is used as an auxiliary means of removing these heavies.

[0094] The present invention focuses on the recovery of rhodium from feed streams within a hydroformylation process. Some embodiments of the present invention are particularly useful for removing rhodium from a concentrated catalyst feed stream (i.e., a catalyst-containing liquid purge stream) after a product (aldehyde) / catalyst separation zone. For example, when an evaporator is used to separate the aldehyde product, some embodiments of the present invention can be used to remove rhodium from the evaporator tailings, which is a catalyst-containing liquid purge stream. As described above, the catalyst in such a liquid purge stream comprises a noble metal and an organophosphorus ligand.

[0095] According to an embodiment of the present invention, a liquid purge stream containing a catalyst is treated with an oxidant to convert an organophosphorus (e.g., phosphorus (III) species) ligand into a corresponding oxide, which is a very poor ligand for phosphorus (V) species and a noble metal. For the purpose of the following discussion, the noble metal will be discussed as rhodium, but it should be understood that the noble metal used in the catalyst may also be other noble metals as disclosed herein. In the presence of a halide-free C1-C6 organic acid or a halide-free phosphorous acid, it is believed that the released rhodium is captured (complexed) by a carboxylate or phosphorous acid to form a water-soluble rhodium complex. In order to maximize the distribution of rhodium in the aqueous phase, the amount of higher molecular weight acids (e.g., acids derived from C7 and higher aldehyde products) should be minimized. This is achieved by treating the purge stream with sufficient oxidant only under mild conditions to maximize the oxidation of the organophosphorus while minimizing the oxidation of the residual aldehydes. In addition, it is preferred to perform this step (e.g., after the product-catalyst separation step) on a concentrated catalyst purge stream having a significantly reduced C7+ aldehyde concentration.

[0096] For purposes of this application, the phrase "halide-free" relative to the acid used during oxidation is used to indicate that no added halide is present in the aqueous phase prior to mixing with the organic phase, although it is recognized that some halide may originate from the organic phase and enter the aqueous phase. In some embodiments, the methods of the present invention will significantly reduce the halide: noble metal ratio (<0.01:1) during processing, resulting in a noble metal-organophosphite complex that is substantially free of halide.

[0097] The oxidizing agent used in some embodiments of the present invention is preferably oxygen, air, oxygen diluted in an inert gas (e.g., nitrogen, argon, helium, etc.), hydrogen peroxide, alkyl peroxides, aryl peroxides, dialkyl peroxides, diaryl peroxides, or a peroxyacid having less than 9 carbon atoms (e.g., benzoyl peroxide).

[0098] Once the noble metal is transferred to the aqueous phase, the organic phase containing heavies and other unwanted materials (including oxidized ligands) is removed. The noble metal component of the catalyst is then reconstituted by reversing the process by contacting the aqueous phase with an organic phase under a syngas atmosphere (reducing environment), wherein the organic phase contains water-insoluble, hydrolyzable organophosphorus ligands in recycled olefins from the hydroformylation process. This advantageously forms a noble metal-organophosphorus complex (e.g., a new catalyst complex) in an active catalyst resting state. Because the noble metal-organophosphorus complex is insoluble in water, it migrates into the organic phase, which can then be separated and returned to the hydroformylation process.

[0099] Without being bound by theory, it is believed that by using low-activity olefins (for example, recycle olefins from hydroformylation process) dissolving water-insoluble hydrolyzable organophosphorus ligands under the condition of regeneration catalyst, very few aldehydes are generated in the method. Compared with olefins, the aldehydes with larger polarity will tend to dissolve the remaining non-halide acid (for example, C1-C6 organic acid or phosphorous acid) back in the organic phase, and therefore will be disadvantageously incorporated in the hydroformylation process. In addition, aldehydes will tend to increase the density of the recovery solvent, potentially reducing the efficiency of the phase separation step (d). By using high molecular weight, less reactive recycle olefin streams, no new material is introduced in the hydroformylation process, and the acidic residues that return to the hydroformylation process are minimized. Lower acidity will reduce the formation of heavies and therefore potentially reduce the needs of the purge stream forward.

[0100] The conditions for converting the water-soluble noble metal material back into an organic soluble noble metal-organophosphorus complex (i.e., by contacting the water-insoluble hydrolyzable organophosphorus ligand in the recycled olefin) are not strictly critical. Conditions should be selected to be sufficient to convert the noble metal into a noble metal catalyst precursor or an active noble metal catalyst while minimizing the hydroformylation conversion of any contained olefin in the organic phase. In certain embodiments, the step of contacting the two phases is carried out at 1 bar or higher synthesis gas pressure by mixing the aqueous phase with a separate organic phase (comprising a water-insoluble hydrolyzable organophosphorus ligand and recycled olefins from the hydroformylation process) under a synthesis gas atmosphere. In certain embodiments, such contacting steps are carried out at 10 bar or higher synthesis gas pressures. In certain embodiments, such contacting is carried out at 20 bar or higher synthesis gas pressures, although it is not believed that there is any advantage associated with contacting at a synthesis gas pressure greater than 20 bar. Therefore, in certain embodiments, such contacting is carried out at a synthesis gas pressure of at most 20 bar. In some embodiments, the step of contacting the two phases by mixing the aqueous phase with a separate organic phase (comprising a water-insoluble hydrolyzable organophosphorus ligand and recycled olefins from a hydroformylation process) under a syngas atmosphere is performed at a temperature between 0°C and 150°C. In some embodiments, such contacting step is performed at a temperature of 30°C or higher. In some embodiments, such contacting is performed at a temperature of 80°C or higher. In some embodiments, such contacting is performed at a temperature of 80°C to 150°C. In some embodiments, such contacting is performed at a temperature of 80°C to 120°C.

[0101] The hydroformylation reaction of olefins contained in the organic phase will tend to increase the polar organic content of the organic phase, which will tend to enhance the solubility of any acid in the aqueous phase; this would be undesirable. The concentration of the resulting aldehyde and any acid contained in the organic phase can be easily monitored by conventional analytical techniques such as gas chromatography. The use of highly hindered recycled olefins can be particularly beneficial here because their conversion rate to aldehydes is very slow.

[0102] Surprisingly, despite the presence of high concentrations of C1-C6 acids or phosphorous acid in water, minimal hydrolysis of the hydrolyzable ligands was achieved under the conditions necessary to achieve precious metal recovery. Without being bound by theory, it is believed that by minimizing the polar organic content of the organic phase, the water-insoluble hydrolyzable organophosphorus ligands are protected from acid-catalyzed hydrolysis by minimizing the amount of water and acid present in the organic phase.

[0103] In an optional embodiment, the organic phase containing the noble metal-organophosphorus complex can be washed with an aqueous wash solution containing a water-soluble amine before returning the organic phase to the hydroformylation zone. In some embodiments, the water-soluble amine has the following structure:

[0104]

[0105] Where R 1 , R 2 and R 3 are each independently alkyl and ethoxylate, and wherein R 1 , R 2 and R 3 In some embodiments, no more than one of R 1 , R 2 and R 3 In some embodiments, R 1 , R 2 and R 3 For the purposes of this disclosure, an "ethoxylate" is (-CH 2 -CH 2 -O) n The moiety H, wherein n is equal to 1 or 2. A particularly desirable water-soluble organic amine for use in embodiments of the present invention is triethanolamine.

[0106] Advantageously, the water-soluble amine has the following two properties: 1) it is weakly basic to avoid the formation of heavies in the reaction zone; and 2) it is water-soluble to avoid accumulation in the reaction fluid. The basicity or alkalinity of a water-soluble amine is generally reported as the pKa of the conjugate acid, which is advantageously 5 to 11 at the temperature of the extraction zone. In some embodiments, the pKa is 6.0 to 9.5, and in some particularly desirable embodiments, 6.5 to 9.0. Candidates for amines can be tested for heavies formation by heating the product aldehyde and amine at elevated temperatures. At the hydroformylation temperature, an acceptable amine will exhibit less than 1 gram of heavies formation / liter of test solution / day. The amount of heavies formed can be easily determined by gas chromatography or liquid chromatography, as known to those skilled in the art. The minimum water solubility is at least 5% soluble in water at 25°C and preferably miscible with water at 25°C and above.

[0107] The water-soluble amine solution is used in an amount sufficient to generate a separate phase when heated under synthesis gas. A mixture of amines can be used. In some embodiments, the water-soluble amine solution is used in an amount of 2.5 to 50% by weight of the amine solution in the organic phase with the noble metal-organophosphorus complex, based on the total weight of the organic phase. In some embodiments, the water-soluble amine solution is used in an amount of 2.5 to 10 weight percent amine solution in such an organic phase, based on the total weight of the organic phase. In some embodiments, the water-soluble amine is used in an amount of 2.5 to 5% by weight amine solution in such an organic phase, based on the total weight of the organic phase. The concentration of amines in the aqueous solution can be measured by conventional techniques known to those skilled in the art, including, for example, gas chromatography and liquid chromatography. The amount of the amine solution is not critical, but should be sufficient to generate a separate phase to be decanted.

[0108] In some embodiments, an aqueous wash with a water-soluble amine may be present when the aqueous phase is contacted with a solution of a water-insoluble hydrolyzable organophosphorus ligand at least partially dissolved in the recycled olefin to form a noble metal-organophosphorus complex in the organic phase. In such embodiments, the presence of a water-soluble amine may advantageously prevent or reduce hydrolysis of fresh hydrolyzable ligands catalyzed by residual C1-C6 organic acid or phosphorous acid.

[0109] Residual water-soluble amines as described herein may be present in the feed stream returned to the hydroformylation process and may optionally be removed by an aqueous extractor which may have been in place to control the acidity of the system as described in U.S. Pat. Nos. 5,741,942 and 5,741,944. Alternatively, the organic phase may be batchwise or periodically water washed with the noble metal-organophosphorus complex or a portion thereof to remove water-soluble amines and other polar contaminants.

[0110] The amount of water-insoluble, hydrolyzable organophosphorus ligand added to form the noble metal-organophosphorus complex in the organic phase is not particularly critical, but in some embodiments should constitute at least 2 equivalents of phosphorus (III) per mole of noble metal, in some embodiments greater than 10 equivalents per mole of noble metal, and in some embodiments greater than 15 equivalents per mole of noble metal. There does not appear to be any particular advantage in adding more than 20 moles of hydrolyzable organophosphorus ligand per mole of noble metal, and the total amount added is generally limited by the solubility of the ligand in the solvent and the amount of ligand to be charged to the hydroformylation zone.

[0111] Exemplary non-optically active aldehyde products that can be prepared in a hydroformylation process to which an organic phase comprising a noble metal-organophosphorus complex from the process of the present invention is added include, for example, heptanal, octanal, nonanal, 2-methyl-1-octanal, 2-ethyl 1-heptanal, 3-propyl 1-hexanal, decanal, adipaldehyde, 2-methylglutaraldehyde, 2-methyl adipaldehyde, 3-methyl adipaldehyde, 2-methyl-1-nonanal, undecanal, 2-methyl 1-decanal, dodecanal, 2-methyl 1-undecanal, tridecanal, 2-methyl 1-tridecanal, 2-ethyl 1-dodecanal, 3-propyl-1-undecanal, pentadecanal, 2-methyl-1-tetradecanal, hexadecanal, 2-methyl-1-pentadecanal, heptadecanal, 2-methyl-1-hexadecanal, octadecanal, 2-methyl-1-heptadecanal, nonadecanal, 2-methyl-1-octadecanal, 2-ethyl-1-heptadecanal, 3-propyl-1-hexadecanal, and the like.

[0112] Some embodiments of the invention will now be described in more detail in the following examples.

[0113] Examples

[0114] Unless otherwise indicated, all parts and percentages in the following examples are by weight. Unless otherwise indicated, pressures are given as gauge pressures. Rhodium concentrations are determined by atomic absorption ("AA") using an air / acetylene flame. It has been found that this technique cannot reliably quantify clustered rhodium; therefore, this method can be used to indicate "rhodium loss" (e.g., undetectable rhodium aggregation or otherwise no longer in solution). Color changes (starting from a colorless or light yellow solution), such as darkening or formation of a black film or solid also indicate rhodium catalyst degradation.

[0115] Ligand A is a commercially available organic monophosphite, tris(2,4-di-tert-butylphenyl)phosphite:

[0116]

[0117] Ligand A

[0118] Catalyst A is a hydroformylation catalyst solution having the following composition:

[0119] <![CDATA[ Components ]]> <![CDATA[ Concentration (weight %) ]]> Isononanal 39.5 Isononanal heavy substances 50 C8 olefins 10 Ligand A 0.5 rhodium 0.04

[0120] General Procedure for the Hydroformylation Process

[0121] The catalyst-containing solution mentioned in the following examples of the present invention is in N 2 -filled purge box and transferred by vacuum to a 100 mL Parr microreactor. The catalyst-containing solution was then preheated for 30 minutes with stirring (500 rpm) at the desired reactor temperature in the presence of C8 olefins and 1:1 synthesis gas (equal parts carbon monoxide:hydrogen). During this time, a pressure of about 50 psig 1:1 gas was established using a Brooks 5866 flow meter. After a 30 minute catalyst activation period, the reactor pressure was increased to the desired reactor pressure. The pressure was held constant for the desired run time and the total gas uptake was measured using a Brooks 0151E accumulator.

[0122] General procedure for rhodium oxide extraction experiments:

[0123] Catalyst A was weighed into a 60 mL glass bottle, a stir bar was added, and the aqueous extract solution was added, followed by any additives. The resulting two-phase solution was stirred in an oil bath at the desired temperature and bubbled continuously with plant air at atmospheric pressure. After the reaction was complete, the catalyst solution bottle was removed from the oil bath, the phases were allowed to separate for 5 minutes, and samples (typically 0.2 g) were removed from each phase and analyzed with AA.

[0124] Comparative Example 1

[0125] Catalyst A (20 g) was bubbled with air at 70°C for 4 hours with magnetic stirring. After oxidation with air, the catalyst solution was treated with deionized water (20 g) and the two-phase solution was stirred at room temperature for 1 hour. The phases were separated and samples were taken for AA analysis.

[0126] Comparative Example 2

[0127] Catalyst A (20 g) was treated with deionized water (20 g) and air was bubbled through at 70° C. for 4 hours with magnetic stirring. After the oxidation treatment with air, the phases were separated and samples were taken for AA analysis.

[0128] Comparative Example 3

[0129] 4.0 g of glacial acetic acid was added to the biphasic catalyst solution from Comparative Example 2 and the biphasic solution was stirred at room temperature for 2 hours. The phases were separated and samples were taken for AA analysis.

[0130] Example 1 of the present invention

[0131] The two-phase catalyst solution containing acetic acid from Comparative Example 3 was bubbled with air at 70°C for 4 hours with magnetic stirring. During this time, the aqueous phase exhibited a clear golden color. After oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0132] Comparative Example 4

[0133] The biphasic catalyst solution from Inventive Example 1 was heated and magnetically stirred overnight at 70° C. in the absence of air bubbling. The phases were separated and sampled for AA analysis.

[0134] The results of Comparative Examples 1-4 and Inventive Example 1 are summarized in Table 1. As used herein, particularly in the tables, Comparative Examples may be abbreviated as "CE". Inventive Examples may be abbreviated as "IE".

[0135] Table 1.

[0136]

[0137] Comparative Examples 1-4 and Inventive Example 1 show that successful transfer of precious metals from the organic phase to the aqueous phase occurs only when air (oxidant), water and acetic acid (C2 acid) are all present. However, Comparative Example 4 shows that continued heating in the absence of an oxidant will result in loss of rhodium from both phases.

[0138] Example 2 of the present invention

[0139] Catalyst A (20 g) was treated with 20% aqueous acetic acid (20 g) and air was bubbled through at 65° C. for 12 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0140] Example 3 of the present invention

[0141] Catalyst A (5 g) was treated with 20% aqueous acetic acid (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0142] Example 4a of the present invention

[0143] Catalyst A (20 g) was treated with 20% aqueous acetic acid (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0144] Example 4b of the present invention

[0145] The aqueous phase was removed from the two-phase solution obtained from Example 4a of the present invention. The organic phase was recycled and treated with 20% aqueous acetic acid (20 g). Air was bubbled through the two-phase solution at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0146] The results of Examples 2-4 of the present invention are summarized in Table 2.

[0147] Table 2

[0148]

[0149] Comparative Example 4 (from Table 1) and Inventive Example 2 show that the oxidation treatment should be only as long as necessary to remove the rhodium from the organic phase, and that the continued presence of the oxidant until the next step in the process can help avoid loss of precious metals to insoluble metals. Inventive Examples 2-4 show that extended treatment has minimal effect. Inventive Example 4b shows that a second extraction is the preferred way to obtain maximum precious metal recovery (rather than an extended single treatment).

[0150] Example 5a of the present invention

[0151] Catalyst A (10 g) was treated with 50% aqueous acetic acid (10 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0152] Example 5b of the present invention

[0153] The biphasic catalyst solution obtained from inventive example 5a was bubbled with air for another 4 hours at 65°C with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0154] Example 5c of the present invention

[0155] The aqueous phase was removed from the two-phase solution obtained from Example 5b of the present invention. The organic phase was recycled and treated with 33% aqueous acetic acid (3.8 g). Air was bubbled through the two-phase solution at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0156] Example 6 of the present invention

[0157] Catalyst A (10 g) was treated with 70% aqueous acetic acid (10 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0158] The results of Inventive Examples 5-6 are summarized in Table 3. Similar results as obtained in the previous examples were found in Inventive Examples 5-6 using more concentrated acid. Comparison of Inventive Examples 4a and 5a shows that higher acid content results in improved extraction of precious metals into the aqueous phase.

[0159] Table 3

[0160]

[0161] It should be noted that the bubbling process tends to remove organics and / or water at this equipment scale. Therefore, the total metal mass balance may appear to be in excess of 100%, but the relative distribution of the metals between the phases is evident.

[0162] Comparative Example 5

[0163] Catalyst A (20 g) was treated with 20% aqueous nonanoic acid (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0164] Comparative Example 6

[0165] Catalyst A (20 g) was treated with 1 molar aqueous ammonium acetate solution (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0166] Example 7 of the present invention

[0167] Catalyst A (20 g) was treated with 50% aqueous citric acid solution (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0168] Example 8 of the present invention

[0169] Catalyst A (20 g) was treated with 50% aqueous phosphorous acid (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0170] Example 9 of the present invention

[0171] Catalyst A (20 g) was treated with 50% aqueous glutaric acid (20 g) and air was bubbled through at 65° C. for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0172] Example 10 of the present invention

[0173] A catalyst solution prepared from Rh(CO)2acac (0.010 g), ligand A (0.10 g) and isononanal (10 g) was treated with 50% aqueous propionic acid (10 g) and air was bubbled at 65°C for 4 hours with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0174] The results of Comparative Examples 5-6 and Inventive Examples 7-10 are summarized in Table 4. As shown in Table 4, a variety of components were tested. It is clear that not only the carboxylate portion is critical to recovery, but also the acid form is critical (e.g., acetate is ineffective). Higher acids such as nonanoic acid are ineffective.

[0175] Table 4

[0176]

[0177] Example 11 of the present invention

[0178] Catalyst A (10 g) was treated with 50% aqueous acetic acid (10 g) and air was bubbled through for 24 hours at ambient temperature with magnetic stirring. After the oxidation treatment, the phases were separated and samples were taken for AA analysis.

[0179] Example 12a of the present invention

[0180] Catalyst A (10 g) was treated with 50% aqueous acetic acid (10 g) and 30% aqueous hydrogen peroxide (0.10 g) at ambient temperature for 24 hours with magnetic stirring. After the oxidation treatment with hydrogen peroxide, the phases were separated and sampled for AA analysis.

[0181] Example 12b of the present invention

[0182] The biphasic solution from inventive example 12a was treated with additional 30% aqueous hydrogen peroxide (0.30 g) at ambient temperature for 96 hours with magnetic stirring. After oxidative treatment with hydrogen peroxide, the phases were separated and sampled for AA analysis.

[0183] The results for inventive examples 11 and 12 are summarized in Table 5. Using hydrogen peroxide as the oxidant at relatively low temperatures gave moderate results, but outperformed comparable air oxidation over the same time period.

[0184] Table 5

[0185]

[0186] The following example considers the extraction of rhodium from an aqueous phase into an organic recovery solvent.

[0187] Example 13 of the present invention

[0188] 10.0 g of rhodium acetic acid aqueous solution (initial Rh concentration = 163 ppmw, about 40% acetic acid) was weighed into a 60 mL glass bottle, followed by 10.0 g of mixed C9 aldehydes containing 1.0 wt% ligand A (which also contained 5.2% n-octane, unreacted olefins and other minor components). The resulting two-phase solution was heated under N 2 The reaction mixture was stirred at 400 rpm until the ligand dissolved and the solution was charged to a Parr reactor and heated to 100° C. for 3 hours under 55 psig 1:1 syngas with stirring (700 rpm). After 1 hour and 3 hours, the catalyst solution was collected and both phases were sampled for Rh AA analysis.

[0189] The results of Example 13 of the present invention are summarized in Table 6.

[0190] Table 6

[0191]

[0192] Example 14 of the present invention

[0193] 10.0 g of an aqueous rhodium acetic acid solution (initial Rh concentration = 183 ppmw, about 40% acetic acid) was weighed into a 60 mL glass bottle, followed by 10.0 g of mixed butene-dimer containing 1.0 wt% ligand A. The resulting two-phase solution was bubbled with nitrogen for 5 minutes, then bubbled with 1:1 synthesis gas for 2 minutes at ambient temperature and pressure. Next, the solution bottle was capped and sealed with parafilm and heated to 70°C for 4 hours, and samples were taken from the two phases after 1, 2 and 4 hours after the layers were phase separated. Thereafter, the two-phase catalyst solution was again bubbled with 1:1 synthesis gas (2 minutes) and heated to 70°C for 1 hour at ambient pressure; samples were collected for Rh AA analysis. Finally, the catalyst solution was heated to 70°C for 1 hour under 55 psig 1:1 synthesis gas in a Parr reactor with stirring (700 rpm). Samples were collected for Rh AA analysis.

[0194] The results of Inventive Example 14 are summarized in Table 7 (nm = not measured).

[0195] Table 7

[0196]

[0197] This example shows the conditions for recovering rhodium from the aqueous phase. Although treatment with synthesis gas at atmospheric pressure is effective for non-polar olefins and ligand A, higher pressures give better results. In the absence of ligand A, severe rhodium losses were observed (rhodium black was observed) when higher pressures were used. Butene-dimers or butane-dimers were used to simulate the less reactive internal olefins generated by hydroformylation of 1-octene. Under the conditions (i.e. temperature and pressure) used in the recovery step, very little of these highly branched olefins was converted into aldehydes.

[0198] If mixed C9-aldehydes are used as solvent instead of butene dimer, the phase separation is much slower, thus teaching that non-polar olefins are preferred solvents for pure aldehydes.

[0199] Example 15 of the present invention

[0200] Into a 60 mL glass bottle, 10.0 g of an aqueous solution of rhodium in acetic acid (initial Rh concentration = 183 ppmw, about 40% acetic acid) was weighed, followed by 10.0 g of a mixed butene-dimer containing 1.0 wt% of ligand A. The resulting two-phase solution was heated under N 2 The mixture was stirred at 400 rpm until the ligand dissolved and the solution was charged to a Parr reactor and heated to 70°C under 55 psig 1:1 syngas for 2 hours with stirring (700 rpm). After 1 hour and 2 hours, the catalyst solution was collected and both phases were sampled for Rh AA analysis.

[0201] The results are shown in Table 8. Inventive Example 15 showed excellent transfer from the aqueous phase to the organic phase under these conditions.

[0202] Table 8

[0203]

[0204] Example 16 of the present invention

[0205] Catalyst A (20 g) was treated with 20% aqueous acetic acid (20 g) and the resulting two-phase solution was continuously bubbled with air at 65° C. for 4 hours with stirring. The phases were separated and the aqueous acetic acid extract was collected and bubbled with nitrogen for 30 minutes at ambient temperature. A 1 wt % solution of Ligand A dissolved in isononanal (28 g) was added (which also contained 5.2% n-octane, unreacted olefins and other minor components) and the two-phase mixture was charged to a Parr reactor and heated to 100° C. under 300 psig 1:1 syngas for 1 hour with stirring (700 rpm). After treatment, the reactor was cooled to ambient temperature for 1 hour, the catalyst solution was collected and both phases were sampled for RhAA analysis.

[0206] The results for Inventive Example 16 are shown in Table 9. Inventive Example 16 showed excellent transfer from the aqueous phase to the organic recovery phase under these conditions.

[0207] Table 9

[0208]

[0209] Example 17 of the present invention

[0210] Catalyst A (20 g) was added to a 100 mL glass bottle, followed by 20% aqueous acetic acid (20 g). The resulting two-phase solution was bubbled with air at 65 °C for 4 hours with stirring and cooled to room temperature. The phases were separated and both layers were sampled for RhAA analysis. Next, the aqueous layer was collected and heated at ambient temperature with N 2 Bubbling was continued for about 1 hour. A solution of 1 wt% ligand A dissolved in isononanal (20 g) (which also contained 5.2% n-octane, unreacted olefins and other minor components) was added to the aqueous solution, and the resulting two-phase mixture was charged into a Parr reactor and heated at 100°C and 300 psig 1:1 H 2 The reactor was cooled to ambient temperature and the mixture was collected; both phases were sampled for Rh AA analysis. The results of the oxidation treatment and syngas recovery steps are summarized in Table 10.

[0211] Table 10

[0212]

[0213] Example 18 of the present invention

[0214] Next, the aqueous solution from Inventive Example 17 was removed from the biphasic catalyst solution and the organic catalyst solution was recharged into the Parr reactor along with 5.0 mL of mixed butene dimers and subjected to the hydroformylation test at 85° C. and 250 psig syngas for 7 hours. As summarized in Table 11, when subjected to the hydroformylation test, the recovered hydroformylation catalyst exhibited about 80% of the activity of Catalyst A, consistent with the about 80% recovery of dissolved rhodium.

[0215] Table 11

[0216]

Claims

1. A process for recovering rhodium from a catalyst purge stream from a C6 or higher olefin hydroformylation process, the process comprising: (a) treating a catalyst-containing liquid purge stream from said hydroformylation process with an oxidizing agent in the presence of a separate liquid aqueous phase comprising a halide-free acid at a temperature sufficient to effect oxidation of a substantial portion of the contained organophosphorus ligands, wherein the halide-free acid is a C1-C6 organic acid or phosphorous acid; (b) recovering the aqueous phase; (c) contacting the aqueous phase with a separate organic phase by mixing the two phases under a synthesis gas atmosphere, wherein the separate organic phase comprises a water-insoluble, hydrolyzable organophosphorus ligand and a recycled olefin from a hydroformylation process; and (d) separating the organic phase to be recycled back to the hydroformylation process; The hydrolyzable organophosphorus ligand is a trivalent phosphorus containing at least one PZ bond. (III) a ligand wherein Z is oxygen, nitrogen, chlorine, fluorine or bromine; wherein "majority" of the organophosphorus ligands contained means 50% by weight or more of the organophosphorus ligands contained in the liquid purge stream; Therein the recycle olefins comprise a stream which has been recovered after a hydroformylation process or which is derived from such a stream, such that the olefins contained have been passed through a hydroformylation process at least once.

2. The process according to claim 1 further comprises, after recovering the aqueous phase in step (b), treating the remaining organic phase from step (a) with water or with an aqueous solution comprising a halide-free C1-C6 organic acid or phosphorous acid or with an oxidizing agent in the presence of a separate liquid aqueous phase comprising a halide-free C1-C6 organic acid or phosphorous acid, recovering a second aqueous phase, and combining the second aqueous phase with the aqueous phase in step (b) before step (c).

3. The process according to claim 1 or 2, further comprising washing the organic phase from step (d) with an aqueous wash liquid before sending the organic phase to the hydroformylation process, wherein the aqueous wash liquid comprises a water-soluble amine.

4. The method according to claim 1 or 2, wherein the halide-free organic acid in step (a) is a halide-free C1-C2 organic acid.

5. The process of claim 1 or 2, wherein the recycle olefin is from a different hydroformylation process than the catalyst-containing liquid purge stream.

6. The method of claim 1 or 2, wherein the organophosphorus ligand is a tertiary organophosphorus ligand.

7. The method according to claim 1 or 2, further comprising bubbling the aqueous phase with an inert gas or a synthetic gas after recovering the aqueous phase in step (b) and before introducing the water-insoluble hydrolyzable organophosphorus ligand in step (c).

8. The process according to claim 1 or 2, wherein the oxidizing agent is oxygen, air, oxygen diluted in an inert gas, hydrogen peroxide, an alkyl peroxide, an aryl peroxide, a dialkyl peroxide, a diaryl peroxide or a peroxyacid having less than 9 carbon atoms.

9. The process of claim 1 or 2, wherein the recycle olefin is C6 or higher and has a lower hydroformylation activity than the olefin feed used in the hydroformylation process from which the catalyst-containing liquid purge stream is generated.

10. The process of claim 1 or 2, wherein the recycle olefin is C6 or higher and has a higher average degree of branching than the olefin feed used in the hydroformylation process from which the catalyst-containing liquid purge stream is generated.

11. The method according to claim 1 or 2, in, The contacting of the aqueous phase with the separate organic phase in step (c) is carried out at a temperature of 0°C to 150°C.

12. The method according to claim 1 or 2, in, The contacting of the aqueous phase with the separate organic phase in step (c) is carried out at a synthesis gas pressure of at least 1 bar.

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