RU2804660C2 - Catalyst composition containing a combination of monophospine, tetraphosphine ligand and method for hydroformylation with its application - Google Patents

Abstract

FIELD: catalyst compositions for hydroformylation processes.

SUBSTANCE: catalyst composition for the hydroformylation process comprises: (a) a transition metal which is rhodium; (b) a monophosphine; and (c) a tetraphosphine having the following structure:where each P is a phosphorus atom and each R¹ -R⁴⁶ is independently hydrogen, a C1-C8 alkyl group, an aryl group, an alkaryl group, an alkoxy group, a haloalkyl group, a haloaryl group, or a halogen, and wherein the catalyst composition comprises at least 40 moles of monophosphine per mole of transition metal. The invention also relates to a hydroformylation process.

EFFECT: increased regioselectivity N:I> =13 by adding a tetradentate phosphine ligand as part of the catalyst composition.

8 cl, 1 dwg, 6 tbl, 17 ex

Description

Field of technology

The present invention relates to catalyst compositions for hydroformylation processes and to hydroformylation methods using certain catalysts.

State of the art

It is known in the art that aldehydes can be readily prepared by reacting an olefinically unsaturated compound with carbon monoxide and hydrogen in the presence of a solubilized rhodium-triorganophosphorus ligand complex catalyst, and that the preferred type of such processes involves continuous hydroformylation. For example, US Pat. No. 3,527,809 describes the hydroformylation of alpha-olefins to produce aldehydes at low temperatures and pressures. This method uses specific rhodium complexes to efficiently catalyze, under a specific set of variables in the presence of selected triorganophosphorus ligands, the hydroformylation of olefins with hydrogen and carbon monoxide.

Among the catalysts described in US Pat. No. 3,527,809 are compounds containing rhodium and triarylphosphorus ligands, in particular triarylphosphine ligands, an example of which is triphenylphosphine (“TPP”). In industrial hydroformylation processes, the rhodium-TPP catalyst has been used successfully for decades, and a key aspect of the operation is the use of a large excess of TPP compared to rhodium. For example, industrial processes for hydroformylation of propylene often operate with TPP concentrations of 10-12 wt.% based on the total weight of the reaction liquid. Such high concentrations of TPP are used to achieve the desired product regioselectivity and improve catalyst stability.

For hydroformylation processes, product regioselectivity is usually expressed as the ratio of linear (or normal) product to branched (or iso) aldehyde product. In this context, this ratio of linear (or normal) product to branched (or iso) aldehyde product will be referred to as the “N:I” or “N:I” ratio. Although rhodium-TPP catalysis is an effective technology, it is difficult to increase the N:I ratio to values greater than about 10:1. While a branched product has value, a linear product is often preferred. Selectivity to linear products can be increased by using a different catalyst promoter, for example certain chelating organopolyphosphorus ligands (e.g. certain bisphosphites) are known to exhibit N:I greater than 10:1, but such changes in industrial settings may involve dumping the existing catalyst, reducing rhodium by recovery of precious metals (“VBM”), possible changes to equipment, etc. The production losses, VBM costs, and acquisition of process equipment associated with such activities can be quite costly.

It would be desirable to have a simple means of increasing N:I for an industrial rhodium-TPP process that does not involve removing all catalyst from the reaction zone, lengthy shutdowns, and/or installing expensive process equipment.

Brief description of the invention

The present invention relates to a catalyst composition for hydroformylation processes that provides a number of advantages in various embodiments. For example, in some embodiments, it has surprisingly been discovered that the N:I of a rhodium monophosphine hydroformylation process for propylene can be increased to ≥13:1 by adding a tetradentate phosphine ligand as part of the catalyst composition. When incorporating a catalyst composition into a hydroformylation process, in some embodiments, the methods of the present invention advantageously do not require replacement of the existing catalyst, extensive shutdowns, extensive cleaning of the reaction system, and/or installation of expensive process equipment (e.g., additional heat exchangers, water extractor, etc.).

In one aspect, the catalyst composition for a hydroformylation process comprises:

(a) transition metal;

(b) monophosphine; And

(c) tetraphosphine having the following structure:

wherein each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, aryl group, alkaryl group, alkoxy group, haloalkyl group, haloaryl group or halogen, and wherein the catalyst composition contains at least at least 40 moles of monophosphine per mole of transition metal.

In one aspect, the hydroformylation method includes contacting an olefin, hydrogen and carbon monoxide in the presence of a catalyst in a reaction liquid in a reactor, wherein the catalyst comprises:

(a) transition metal;

(b) monophosphine; And

(c) tetraphosphine having the following structure:

wherein each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, aryl group, alkaryl group, alkoxy group, haloalkyl group, haloaryl group or halogen, and wherein monophosphine is present in the reaction liquid in reactor in an amount greater than or equal to 1.5 wt.% of the total weight of the reaction liquid in the reactor.

These and other embodiments of the invention are described in more detail in the Detailed Description of the Invention section below.

Detailed description of the invention

All references to the Periodic Table of the Elements and the various groups therein are to the version published in the CRC Handbook of Chemistry and Physics, 72nd Ed. (1991-1992) CRC Press, on page I-11.

Unless otherwise stated or otherwise implied by context, all values expressed in parts and percentages are by weight and all test methods are generally accepted at the time this application is filed. As a matter of United States patent practice, the contents of any patent, patent application, or publication referenced in its entirety are hereby incorporated by reference in its entirety (or its equivalent U.S. version is incorporated by reference), especially with respect to the description of definitions (to the extent which is not inconsistent with any definitions specifically stated herein) and general knowledge in the art.

As used herein, the use of nouns and nouns together with the phrases “at least one” and “one or more” are used interchangeably. The terms “comprises,” “includes,” and variations thereof are not intended to be limiting when those terms appear in the specification and claims.

Also in this document, the indication of numeric ranges by endpoints includes all numbers included in the given range (for example, from 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). d.). It is to be understood within the scope of the present invention, and as one skilled in the art would understand, that a numerical range is intended to be inclusive and encompass all possible sub-ranges that fall within a given range. For example, the range 1 to 100 is intended to express 1.01 to 100, 1 to 99.99, 1.01 to 99.99, 40 to 60, 1 to 55, etc. Also in this specification, listings of numerical ranges and/or numerical values, including such listings in claims, may be considered to include the term “about.” In such cases, the term "about" refers to numerical ranges and/or numerical values that are substantially the same as those given herein.

In this document, the term “wt. ppm" means parts per million by mass.

For purposes of the present invention, the term “hydrocarbon” is intended to include all valid compounds containing at least one hydrogen atom and one carbon atom. Such permissible compounds may also contain one or more heteroatoms. In broad terms, acceptable 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.

As used herein, the term “substituted” is intended to include all permissible organic substituents unless otherwise specified. In broad terms, acceptable substituents include acyclic and cyclic, branched and straight-chain, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. Typical substituents include, for example, alkyl, alkyloxy, aryl, aryloxy, hydroxyalkyl, aminoalkyl, in which the number of carbon atoms may range from 1 to 20 or more, preferably 1 to 12, as well as hydroxy, halogen and amino. The corresponding organic compounds may contain one or more acceptable substituents, the same or different acceptable substituents. The present invention is not intended to be limited in any way by the organic substituents permitted.

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 olefin compounds or a reaction mixture containing one or more substituted or unsubstituted olefin compounds into one or more substituted olefin compounds. or unsubstituted aldehydes or a reaction mixture containing one or more substituted or unsubstituted aldehydes. Aldehydes can be asymmetric or non-asymmetric.

The terms "reaction liquid", "reaction medium" and "catalyst solution" are used interchangeably herein and may include, but are not limited to, a mixture containing: (a) a transition metal-monophosphine complex catalyst (e.g., a rhodium complex catalyst -triphenylphosphine), (b) a catalyst based on a transition metal-tetraphosphine complex (for example, a catalyst based on a rhodium-tetraphosphine complex), (c) free monophosphine (for example, triphenylphosphine), (d) free tetraphosphine, (e) formed during reaction aldehyde products, (e) unreacted reactants, (g) a solvent for said transition metal complex catalysts and said free phosphine ligands, and optionally (h) decomposition products of a monophosphine ligand and a tetraphosphine ligand. The reaction fluid may include, but is not limited to, (a) reaction zone fluid, (b) fluid flow en route to the separation zone, (c) separation zone fluid, (d) recycle stream, (e) liquid withdrawn from the reaction or separation zone, (f) liquid in the external cooler, and (g) ligand decomposition products.

The term “ligand degradation products” is intended to include, but is not limited to, any and all compounds resulting from one or more chemical transformations of at least one of the tetraphosphine and/or monophosphine molecules loaded into the reaction liquid. Such compounds may include, but are not limited to, triphosphine or diphosphine compounds resulting from rhodium-promoted cleavage of the parent tetraphosphine, as well as smaller phosphine moieties resulting from these side cleavage reactions. It is also believed that ligand degradation products include alkyldiarylphosphines, which are known to be present in solutions of rhodium-triarylphosphine hydroformylation catalysts (see, for example, US Pat. No. 4,297,239, column 5). Additionally, it is assumed that ligand degradation products include any and all compounds that arise from the oxidation of phosphine moieties. For example, ligand degradation products may include phosphine oxides derived from monophosphine introduced into the process, as a result of partial or complete oxidation of tetraphosphine introduced into the process, or as a result of oxidation of phosphine compounds resulting from side reactions stimulated by rhodium (for example, oxidation of triphosphine compounds derived from the original tetraphosphine).

As used herein, the terms “tetradentate phosphine” and “tetraphosphine” are used interchangeably and are considered to include compounds containing four phosphorus atoms, each of which is bonded to three carbon atoms.

As used herein, the terms “monodentate phosphine” and “monophosphine” are used interchangeably and include compounds that contain one phosphorus atom bonded to three carbon atoms.

As used herein, the terms "rhodium complex", "rhodium complex catalyst" and "catalytic complex" are used interchangeably and are intended to contain at least one rhodium atom with ligands bound or coordinated through electronic interaction. Examples of such ligands include, but are not limited to, monophosphine, tetradentate phosphine, carbon monoxide, propylene and hydrogen.

As used herein, the term “free” phosphine refers to monophosphine or tetraphosphine molecules that are not bound or coordinated to rhodium.

In general, the present invention is directed to a catalyst composition for hydroformylation processes and to a hydroformylation process using certain catalysts. The catalyst composition contains two ligands, monophosphine (eg, triphenylphosphine) and tetraphosphine, as defined hereinafter. The catalyst composition provides a surprising increase in N:I in the hydroformylation process compared to N:I in the hydroformylation process using monophosphine alone, without the disadvantages often associated with changing the ligand used in the catalyst composition.

In one aspect, the catalyst composition for a hydroformylation process contains (a) a transition metal; (b) monophosphine; and (c) tetraphosphine having the following structure:

wherein each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, aryl group, alkaryl group, alkoxy group, haloalkyl group, haloaryl group or halogen, and wherein the catalyst composition contains at least at least 40 moles of monophosphine per mole of transition metal. In some embodiments, the transition metal includes rhodium. Monophosphine, in some embodiments, is one or more of the following: triphenylphosphine, tris(o-tolyl)phosphine, trinaphthylphosphine, tri(p-methoxyphenyl)phosphine, tri(m-chlorophenyl)phosphine, tribenzylphosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine and trioctylphosphine. In some embodiments, the monophosphine is triphenylphosphine. In some embodiments, the catalyst includes a mixture of different types of monophosphines. In some embodiments, R ¹ -R ⁴⁶ are each hydrogen. In some embodiments, the transition metal includes rhodium, the monophosphine is triphenylphosphine, and R ¹ -R ⁴⁶ is each hydrogen.

In one aspect, the hydroformylation method includes contacting an olefin, hydrogen and carbon monoxide in the presence of a catalyst in a reaction liquid in a reactor, wherein the catalyst comprises:

(a) transition metal;

(b) monophosphine; And

(c) tetraphosphine having the following structure:

wherein each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, aryl group, alkaryl group, alkoxy group, haloalkyl group, haloaryl group or halogen, and wherein monophosphine is present in the reaction liquid in reactor in an amount greater than or equal to 1.5 wt.% of the total weight of the reaction liquid in the reactor.

In some embodiments, R ¹ -R ⁴⁶ are each hydrogen.

In some embodiments, the catalyst contains one or more of the following tetraphosphines:

In some embodiments, the transition metal includes rhodium. Monophosphine, in some embodiments, is one or more of the following: triphenylphosphine, tris(o-tolyl)phosphine, trinaphthylphosphine, tri(p-methoxyphenyl)phosphine, tri(m-chlorophenyl)phosphine, tribenzylphosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine and trioctylphosphine. In some embodiments, the monophosphine is triphenylphosphine. In some embodiments, the catalyst includes a mixture of different types of monophosphines. In some embodiments, R ¹ -R ⁴⁶ are each hydrogen. In some embodiments, the olefin includes propylene. In some embodiments, the transition metal includes rhodium, the monophosphine is triphenylphosphine, R ¹ -R ⁴⁶ is each hydrogen, and the olefin is propylene.

Hydrogen and carbon monoxide can be obtained from any suitable source, including petroleum cracking and oil refining operations.

Syngas (from synthesis gas) is the name of a gas mixture containing varying amounts of CO and H ₂ . The methods for its production are well known. Typically, the main components of synthesis gas are hydrogen and CO, but synthesis gas may contain CO ₂ and inert gases such as N ₂ and Ar. The molar ratio of H ₂ to CO varies widely, but is generally in the range of 1:100 to 100:1 and preferably 1:10 to 10:1. Syngas is commercially available and is often used as a fuel source or intermediate for the production of other chemicals. The H ₂ :CO molar ratio for chemical production is often between 3:1 and 1:3 and is typically set in the range of 1:2 to 2:1 for most hydroformylation applications. Synthesis gas mixtures are the preferred source of hydrogen and CO.

Olefinic feedstocks that can be used in the hydroformylation reactions covered by the present invention may be terminally or internally unsaturated and may have linear, branched or cyclic structures. Such olefins may contain from 2 to 20 carbon atoms and may contain one or more ethylenic unsaturated groups. In addition, such olefins may contain groups or substituents that do not significantly adversely affect the hydroformylation process, such as carbonyl, carbonyloxy, oxy, hydroxy, oxycarbonyl, halogen, alkoxy, aryl, alkyl, haloalkyl, and the like. Exemplary olefinic unsaturated compounds include alpha-olefins, internal olefins, alkyl alkenoates, alkenyl alkanoates, alkenyl alkyl ethers, alkenols, and the like, for example ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-octadecene, 2-butene, isobutylene, 2-methylbutene, 2-hexene, 3-hexene, 2-heptene, cyclohexene, propylene dimers, propylene trimers, propylene tetramers, butene dimers, butene trimers , 2-ethyl-1-hexene, styrene, 3-phenyl-1-propene, 1,4-hexadiene, 1,7-octadiene, 3-cyclohexyl-1-butene, etc. It will be understood, of course, that mixtures of different olefin feedstocks can be used if desired. Embodiments of the present invention may be particularly useful in the hydroformylation of C ₃ and higher olefins. Thus, in some embodiments, the olefinic unsaturated feedstocks are alpha-olefins containing from 3 to 20 carbon atoms and internal olefins containing from 3 to 20 carbon atoms, as well as mixtures of feedstocks consisting of such alpha-olefins and olefins with internal double bonds.

The solvent is primarily used in embodiments of the hydroformylation process. Any suitable solvent may be used that does not unduly interfere with the hydroformylation process. By way of illustration, suitable solvents for rhodium catalyzed hydroformylation processes include those described, for example, in US 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, aldehydes, ketones, nitriles, alcohols, esters and aldehyde condensation products. Specific examples of solvents include: tetraglyme, pentanes, cyclohexane, heptanes, benzene, xylene, toluene, diethyl ether, tetrahydrofuran, butyraldehyde and benzonitrile. The organic solvent may also contain dissolved water up to the saturation limit. Exemplary preferred solvents include ketones (eg, acetone and methyl ethyl ketone), esters (eg, ethyl acetate, di-2-ethylhexyl phthalate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), hydrocarbons (eg, toluene), nitrohydrocarbons (eg nitrobenzene), ethers (eg tetrahydrofuran (THF)) and sulfolane. In rhodium-catalyzed hydroformylation processes, it may be preferable to use as the main solvent aldehyde compounds corresponding to the aldehyde products to be produced and/or higher boiling point aldehyde condensation by-products, for example, which can be produced in situ during the process hydroformylation, as described, for example, in US Pat. Nos. 4,148,830 and 4,247,486. Typically, the primary solvent will eventually include both aldehyde products and higher boiling point aldehyde condensation byproducts ("heavies") due to the nature of the continuous process . The amount of solvent is not particularly critical and should only be sufficient to provide the reaction medium with the desired transition metal concentration. Typically, the amount of solvent is from 5 to 95 wt. % based on the total weight of the reaction liquid. Mixtures of solvents can be used.

The catalyst of this invention includes a transition metal, monophosphine and tetraphosphine. In some particularly useful embodiments, the catalyst includes rhodium, monophosphine and tetraphosphine. The most desirable catalyst is free of metal-bound halogens such as chlorine and contains hydrogen, carbon monoxide and at least one of monophosphine and tetraphosphine complexed with metallic rhodium to provide a catalyst that is soluble in the above liquid phase and stable under reaction conditions .

The catalytic metal may include Group 8, 9 and 10 metals selected from rhodium (Rh), cobalt (Co), iridium (Ir), ruthenium (Ru), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt), osmium (Os) and mixtures thereof, with preferred metals being rhodium, cobalt, iridium and ruthenium, more preferred being rhodium, cobalt and ruthenium, especially rhodium.

The number of available coordination sites on such metals is well known in the art. Thus, the catalytically active substances, which may include a mixture of complex catalysts, may contain monomeric, dimeric or higher nuclearity forms, which are preferably characterized by at least one organophosphine-containing complex-forming molecule per metal molecule, e.g. rhodium. For example, it is believed that the catalytically active species of the preferred catalyst used in the hydroformylation reaction may, along with organophosphine ligands, form complexes with carbon monoxide and hydrogen, given the presence of carbon monoxide and hydrogen gas used in the hydroformylation reaction.

In some preferred embodiments, the transition metal includes rhodium. Rhodium can be introduced into the liquid phase in the form of a pre-prepared catalyst, for example, in the form of a stable crystalline solid, hydridocarbonyl-tris(triphenylphosphine)rhodium, RhH(CO)(PPh ₃ ) ₃ . Rhodium can be introduced into a liquid body as a precursor, which is converted in situ into a catalyst. Examples of such a form of the precursor are rhodium carbonyltriphenylphosphine acetylacetonate, Rh ₂ O ₃ , Rh ₄ (CO) ₁₂ , Rh ₆ (CO) ₁₆ and rhodium dicarbonylacetylacetonate. Both the catalyst compounds that will provide the active species in the reaction medium and their preparation are known in the art, see Brown et al., Journal of the Chemical Society, 1970, pp. 2753-2764.

Typically, the optimal catalyst concentration depends on the concentration of the alpha olefin, such as propylene. For example, the higher the propylene concentration, the lower will typically be the catalyst concentration required to achieve a given rate of conversion to aldehyde products in a given reactor size. Recognizing the relationship between partial pressure and concentration, using a higher partial pressure of propylene results in a higher proportion of propylene in the "off gas" of the liquid body. Since it may be necessary to purge a portion of the gas stream from the product recovery zone before recirculating it to the liquid body to remove some of the propane that may be present, the higher the propylene content of the "off gas", the more propylene will be lost in the propane purge stream. Thus, it is necessary to balance the economic value of the propylene lost in the propane purge stream with the capital savings associated with the lower catalyst concentration.

Rhodium complex catalysts can be in homogeneous or heterogeneous form. For example, preformed rhodium hydridocarbonylphosphine ligand catalysts can be prepared and introduced into the hydroformylation reaction mixture. More preferably, rhodium-phosphine ligand complex catalysts can be prepared from rhodium catalyst starting material, which can be introduced into the reaction medium to form the active catalyst in situ. For example, the starting material for rhodium catalyst, namely rhodium dicarbonylacetylacetonate, Rh ₂ O ₃ , Rh ₄ (CO) ₁₂ , Rh ₆ (CO) ₁₆ , Rh(NO ₃ ) ₃ and the like, can be introduced into the reaction mixture along with monophosphine and tetraphosphine to form an active catalyst in situ. In a preferred embodiment, rhodium dicarbonylacetylacetonate is used as a rhodium precursor and is combined with at least one of monophosphine and tetraphosphine in a solvent and introduced into the reactor along with syn gas to form the active catalyst in situ. Additional monophosphine and/or tetraphosphine may be added as needed to achieve and maintain desired concentrations. In any case, it is sufficient for the purposes of this invention that the compounds such as carbon monoxide, hydrogen and monophosphine and tetraphosphine are all ligands that are capable of complexing with the metal, and that the active metal-ligand catalyst is present in the reaction mixture under the conditions , used in the hydroformylation reaction.

In some embodiments, the catalyst composition is formed in a mixing tank by combining a rhodium catalyst precursor with monophosphine and/or tetraphosphine. If the rhodium catalyst precursor is combined with only one of the two ligands before adding to the reactor, the other ligand can be added to the reactor separately to form the catalyst composition in the reactor.

The amount of rhodium complex catalyst present in the reaction liquid should be only the minimum amount necessary to obtain the desired performance. As a rule, rhodium concentrations range from 150 wt. ppm up to 1200 wt. ppm, based on the free metal in the reaction medium, should be sufficient for most processes, although it is generally preferred to use from 150 to 800 wt. ppm of metal and more preferably from 150 to 500 wt. ppm metal.

The amount of monophosphine in the catalyst composition (whether formed entirely in a mixing tank or formed in a reactor) is at least 40 moles of monophosphine per mole of transition metal (rhodium). In some embodiments, the amount of monophosphine in the catalyst composition (whether formed entirely in a mixing tank or formed in a reactor) is from 40 to 350 moles of monophosphine per mole of transition metal (rhodium). The amount of tetraphosphine in the catalyst composition (whether formed entirely in a mixing tank or formed in a reactor) is at least 1 mole of tetraphosphine per mole of transition metal (rhodium). In some embodiments, the amount of tetraphosphine in the catalyst composition (whether formed entirely in a mixing tank or formed in a reactor) is from 1 to 10 moles of tetraphosphine per mole of transition metal (rhodium). The number of moles of monophosphine or tetraphosphine is measured using high performance liquid chromatography (HPLC) as described in the Examples. The number of moles of rhodium is measured by atomic absorption.

Although the tetraphosphine ligand can conceivably be decomposed to one or more monophosphine compounds, the amount of monophosphine in the catalyst and reaction liquid compositions in accordance with embodiments of the present invention is much greater than would be expected to potentially result from decomposition. In other words, the vast majority of the monophosphine in the catalyst composition or reaction liquid is added or loaded into the catalyst composition or reaction liquid to provide a predetermined amount (eg, not derived from the tetraphosphine present in the catalyst composition or reaction liquid).

For commercial operations, the ligand concentration must be maintained by periodic or continuous addition. To do this, the concentrations of ligands in the reaction liquid are usually measured by one or more analytical methods; High performance liquid chromatography (HPLC) is usually preferred. Unless otherwise indicated herein, when referring to the amount of ligand in a reaction, the ligand concentration is determined by HPLC as described in the Examples. Ligand concentrations in such assays are often expressed as mass percentages; thus, it is often convenient to use these devices for continuous operation. In some embodiments, the amount of monophosphine in the reaction liquid in the hydroformylation process reactor is greater than or equal to 1.5 wt.% based on the total weight of the reaction liquid in the reactor. In some embodiments, the amount of monophosphine in the reaction liquid in the hydroformylation process reactor ranges from 1.5 to 13 weight percent of the total weight of the reaction liquid in the reactor. In some embodiments, the amount of tetraphosphine in the reaction liquid in the hydroformylation process reactor is greater than or equal to 0.06 wt.% based on the total weight of the reaction liquid in the reactor. In some embodiments, the amount of tetraphosphine in the reaction liquid in the hydroformylation process reactor is from 0.1 to 9 wt.% of the total weight of the reaction liquid in the reactor. In some embodiments, where each of R ¹ -R ⁴⁶ in the tetraphosphine shown above is hydrogen, the amount of tetraphosphine in the reaction liquid in the hydroformylation process reactor is from 0.1 to 4 wt.% based on the total weight of the reaction liquid in reactor By way of illustration, a preferred catalyst precursor composition consists essentially of a solubilized rhodium complex precursor, at least one of a monophosphine and a tetraphosphine, and a solvent. The monophosphine and or tetraphosphine ligand readily replaces one of the carbonyl ligands of the parent rhodium acetylacetonate complex at room temperature, as evidenced by the evolution of carbon monoxide gas. After introducing the catalyst precursor composition into the reactor, optionally, additional monophosphine or tetraphosphine can then be added to achieve target concentrations in the reaction liquid.

Accordingly, the rhodium-ligand complex catalysts in the reaction liquid of the hydroformylation reactor preferably contain a complex of rhodium with carbon monoxide and at least one of monophosphine and tetraphosphine. In one embodiment, mixtures of rhodium-ligand complexes are used. For example, the catalyst further contains a complex of rhodium with carbon monoxide and tetradentate phosphine in chelated and/or non-chelated form. The catalyst further contains rhodium in complex with one or more monophosphine molecules and carbon monoxide.

In addition to the rhodium complex catalyst, free monophosphine (ie, monophosphine that does not form a complex with the metal) will also be present in the reaction liquid and may also be present in the catalyst composition before entering the reactor depending on the specific composition. The importance of the free ligand is disclosed in US Pat. No. 3,527,809, GB 1,338,225 and Brown et al., supra., pages 2759 and 2761. In some embodiments, the hydroformylation process of the present invention may include 1 wt.% or greater free monophosphine in the reaction medium. The reaction liquid may also contain free tetradentate phosphine. In some such embodiments, the concentration of free tetradentate phosphine may be from 0.1 to 10 moles per mole of rhodium.

Monophosphine compounds that can serve as ligands in embodiments of the present invention are compounds of Formula I:

(Formula I)

wherein P represents a phosphorus atom and each of Y ¹ -Y ³ independently represents an aryl group, an alkaryl group, a cycloalkyl group, a benzyl group, a C3-C8 alkyl group, a C-8 alkoxy group, an aryloxy group, or a halogen group. Illustrative examples include, but are not limited to, triphenylphosphine, tris(o-tolyl)phosphine, trinaphthylphosphine, tri(p-methoxyphenyl)phosphine, tri(m-chlorophenyl)phosphine, tribenzylphosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine, trioctylphosphine, and the like . In some embodiments, the monophosphine compounds may be hindered phosphines, such as those described in US Pat. No. 4,283,562. For example, in some such embodiments, Y ¹ -Y ³ in Formula I may independently be substituted or unsubstituted C3-C8 an alkyl, a substituted or unsubstituted C5-C8 cycloalkyl group or a substituted or unsubstituted C6-C12 aryl group.

In some embodiments, mixtures of monophosphines may be used.

Tetraphosphine compounds that can serve as ligands in embodiments of the present invention are compounds of Formula II:

Formula II

where each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, an aryl group, an alkaryl group, a haloalkyl group, or a halogen. In a preferred embodiment, each of R ¹ -R ⁴⁶ represents hydrogen. Other examples of tetraphosphines that may be used in some embodiments are described elsewhere herein.

In some embodiments, mixtures of tetraphosphines may be used.

Hydroformylation methods and conditions for carrying them out are well known. In a typical embodiment, an olefin (eg, propylene) is hydroformylated in a continuous or semi-continuous manner, with the product separated in a separation zone and the concentrated catalyst solution recycled back to one or more reactors. The recycle procedure typically involves withdrawing a portion of the liquid reaction medium containing the catalyst and the aldehyde product from the hydroformylation reactor, ie the reaction zone, either continuously or batchwise, and recovering the aldehyde product therefrom using a composite membrane such as those disclosed in US Pat. No. 5,430,194 and US 5681473, or the more traditional and preferred method of distilling it, that is, by evaporative separation, in one or more stages at normal, reduced or elevated pressure, based on specific conditions, in a separate distillation zone, and the non-volatile residue containing the metal catalyst is returned to a reaction zone as described, for example, in US Pat. No. 5,288,918. Condensation of volatile materials and their separation and further recovery, for example by further distillation, can be carried out by any conventional method; the crude aldehyde product can, if necessary, be fed for further purification and isomer separation, and any recovered reactants, such as olefin feed and syngas, can be recycled in any desired manner to the hydroformylation zone (reactor). The recovered metal catalyst containing the purified materials from such membrane separation, or the recovered non-volatile metal catalyst containing the residue from such evaporative separation, can be recycled to the hydroformylation zone (reactor) by any conventional means necessary.

In a preferred embodiment, the hydroformylation reaction liquid contains at least some amount of the six basic ingredients or components, i.e. an aldehyde product, a rhodium-triphenylphosphine ligand complex catalyst, a free triphenylphosphine ligand, a rhodium-tetraphosphine ligand complex catalyst, a free tetraphosphine ligand and a solvent for said catalysts and said free ligands. The hydroformylation reaction mixture compositions useful in the present invention can and typically will contain minor amounts of additional ingredients, such as ingredients that were intentionally used in the hydroformylation process or formed in situ during the process. Examples of such ingredients that may also be present include unreacted olefin feedstock, carbon monoxide and hydrogen gases and in situ generated by-products, ligand decomposition compounds, and high boiling liquid aldehyde condensation by-products, as well as other inert materials such as co-solvents or hydrocarbon additives , if they are used.

The hydroformylation reaction conditions used may vary. For example, the total pressure of hydrogen gas, carbon monoxide and olefin feed in the hydroformylation process can range from 1 to 69,000 kPa. However, it is generally preferred that the process be carried out at a total pressure of hydrogen, carbon monoxide and olefin feed gases of less than 14,000 kPa and more preferably less than 3,400 kPa. The minimum total pressure is limited primarily by the amount of reactants required to achieve the target reaction rate. More specifically, the partial pressure of carbon monoxide in the hydroformylation method of the present invention is preferably 1 to 6900 kPa, and more preferably 21 to 5500 kPa, while the partial pressure of hydrogen is preferably 34 to 3400 kPa, and more preferably 69 to 2100 kPa . Typically, the molar ratio of H ₂ :CO gas may be in the range of 1:10 to 100:1 or higher, with a more preferred molar ratio being 1:10 to 10:1.

In general, the hydroformylation process can be carried out at any operating reaction temperature. Advantageously, the hydroformylation process is carried out at a reaction temperature of -25°C to 200°C, preferably from 50°C to 120°C.

The hydroformylation process can be carried out using one or more suitable reactors, such as, for example, a continuous stirred tank reactor (CSTR), a Venturi reactor, a bubble column reactor, or a slurry reactor. The optimal size and shape of the reactor will depend on the type of reactor used. The reaction zone used in the present invention may be a single vessel or may contain two or more separate vessels. The separation zone used in the present invention may be a single container or may contain two or more separate containers. The reaction zone(s) and separation zone(s) used herein may exist in the same vessel or in separate vessels. For example, reactive separation methods, namely reactive distillation, reactive membrane separation and the like, can be carried out in the reaction zone(s).

If desired, the hydroformylation process can be carried out by recycling unconsumed starting materials. The reaction can be carried out in a single reaction zone or in multiple reaction zones, in series or in parallel. The reaction steps can be carried out by gradually adding one of the starting materials to the other. In addition, reaction steps can be combined by adding starting materials together. The starting materials may be introduced into each or all reaction zones sequentially. When complete conversion is undesirable or unattainable, the starting materials can be separated from the product, for example by distillation, and the starting materials are then returned to the reaction zone.

The hydroformylation process can be carried out in reaction equipment lined with glass, stainless steel or a similar type of coating. The reaction zone may be equipped with one or more internal and/or external heat exchanger(s) in order to control excessive temperature fluctuations or prevent any possible "loss" of reaction temperature.

The hydroformylation process according to the present invention may be carried out in one or more steps or steps. The exact number of reaction steps or stages will depend on the optimal balance between capital cost and achieving high catalyst selectivity, activity, lifetime and ease of use, as well as the intrinsic reactivity of the starting materials in question and the stability of the starting material and target reaction product to the reaction conditions.

In one embodiment, the hydroformylation can be carried out in a multi-stage reactor, such as described in US Pat. No. 5,728,893. Such multi-stage reactors can be designed with internal physical barriers that create more than one theoretical reaction stage in the vessel.

In general, it is preferred to carry out the hydroformylation process of the present invention continuously. Continuous hydroformylation processes are well known in the art. The continuous method can be carried out in single-pass mode, i.e. a vapor mixture containing unreacted olefin feed(s) and vaporized aldehyde product is removed from the liquid reaction mixture, from which the aldehyde product is recovered and additional olefin feed(s), carbon monoxide and hydrogen are fed to the liquid reaction medium for the next single pass without recycling the unreacted olefin feed material(s). These types of recycle techniques are well known in the art and may involve recirculation of a liquid containing the metal-organophosphorus complex catalyst separated from the target aldehyde reaction product(s), as described, for example, in US Pat. No. 4,148,830, or a gas recycle technique disclosed, for example, in US patent 4247486, as well as a combination of liquid and gas recirculation techniques, if necessary. The most preferred hydroformylation process according to this invention involves a continuous liquid catalyst recycling process. Suitable techniques for recycling liquid catalyst are disclosed, for example, in US patents 4668651; 4774361; 5102505 and 5110990.

In one embodiment, mixtures of aldehyde products can be separated from other components of the crude reaction mixtures, in which mixtures of aldehydes are prepared by any suitable method, such as, for example, solvent extraction, crystallization, distillation, evaporation, film evaporation, film evaporation, falling film, phase separation, filtration or any combination thereof. It may be desirable to remove aldehyde products from the crude reaction mixture as they are formed through the use of scavenging agents as described in WO 88/08835. One method for separating aldehyde mixtures from other components of crude reaction mixtures is membrane separation, which is described, for example, in US patents 5430194 and 5681473.

As stated above, the desired aldehydes can be recovered from the reaction mixtures. For example, recovery techniques described in US Pat. Nos. 4,148,830 and 4,247,486 may be used. For example, in a continuous liquid catalyst recycling process, a portion of the liquid reaction mixture (containing the aldehyde product, catalyst, etc.), i.e. the reaction liquid removed from the reaction zone can be sent to a separation zone, such as an evaporator/separator, in which the desired aldehyde product can be separated by distillation in one or more stages under normal, reduced or elevated pressure, from the liquid reaction medium condensed and collected in the product receptacle, and further cleaned if necessary. The remaining non-volatile liquid reaction mixture containing the catalyst can then be returned back to the reactor, as may any other volatile materials, such as unreacted olefin, along with any hydrogen and carbon monoxide dissolved in the liquid reaction mixture after being separated from the condensed aldehyde. product, for example, by distillation in any traditional manner.

More specifically, distillation and separation of the desired aldehyde product from the metal-organophosphorus ligand complex catalyst can occur at any suitable temperature. In general, it is preferable that such distillation be carried out at relatively low temperatures, namely below 150°C, and more preferably at a temperature in the range from 50°C to 140°C. In one embodiment, such aldehyde distillation is carried out under reduced pressure, for example, at a total gas pressure that is substantially lower than the total gas pressure used during hydroformylation when low boiling aldehydes (for example, _C4 to _C6 ) are present. or in vacuum when high boiling aldehydes (eg _C7 or higher) are present. For example, it is common practice to subject the liquid medium containing the reaction products removed from the hydroformylation reactor to a decrease in pressure to volatilize a significant portion of the unreacted gases dissolved in the liquid medium, which now contains a much lower concentration of synthesis gas than the reaction medium in a distillation zone, for example an evaporator/separator, in which the desired aldehyde product is distilled. Typically, distillation pressures range from vacuum pressure to a total gas pressure of 340 kPa should be sufficient for most purposes.

In one embodiment, flow gases may be used in the separation zone to facilitate distillation of the aldehyde. Such gas removal evaporators are described, for example, in US Pat. No. 8,404,903.

The elevated concentrations, high temperatures and low partial pressures that occur in the separation zone can adversely affect the catalyst, both in terms of catalyst deactivation and/or increased ligand degradation. As described below in the Examples, an accelerated test procedure, referred to herein as a blocking procedure, was developed to demonstrate the effect of the separation zone on the catalyst in order to evaluate various implementation options.

Exemplary optically inactive aldehyde products of hydroformylation methods according to embodiments of the present invention will depend on the olefin used as reactant and may include, for example, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, 2-methyl-1-butyraldehyde, hexanal , hydroxyhexanal, 2-methyl 1-heptanal, nonanal, 2-methyl-1-octanal, decanal, adipaldehyde, 2-methylglutaraldehyde, 2-methyladipaldehyde, 3-hydroxypropionaldehyde, 6-hydroxyhexanal, alkenals, 2-, 3-, and 4 -pentenal, alkyl-5-formylvalerate, 2-methyl-1-nonanal, 2-methyl-1-decanal, 3-propyl-1-undecanal, pentadecanal, 3-propyl-1-hexadecanal, eicosanal, 2-methyl-1 -tricosanal, pentacosanal, 2-methyl-1-tetracosanal, nonacosanal, 2-methyl-1-octacosanal, hentriacontanal and 2-methyl-1-triacontanal, etc.

In some embodiments, where propylene is an olefin that undergoes a hydroformylation reaction, the product is a mixture of n-butyraldehyde and 2-methylpropionaldehyde. As noted earlier, the ratio of linear (N) to branched (I) isomers, such as the ratio of n-butyraldehyde to 2-methylpropionaldehyde (isobutyraldehyde), is usually described as an N:I or N:I ratio.

In one embodiment, the catalyst contains rhodium, triphenylphosphine at a concentration typically used in commercial processes (eg, 10-12% by weight), and one or more equivalents of tetraphosphine. In such an embodiment, tetraphosphine can simply be added to an existing industrial process without the need to drain the process fluid or remove it from the system. This particular implementation avoids the costs associated with precious metal recovery (PMR) and can be implemented in a short period of time, thereby avoiding long shutdowns. The resulting catalyst will produce a higher percentage of n-butyraldehyde relative to isobutyraldehyde than the rhodium-TPP catalyst.

In one embodiment, the catalyst composition contains rhodium, triphenylphosphine at concentrations (eg, 5-6 wt%) that are lower than those typically used in commercial processes (eg, 10 wt% or more), and one or more equivalents of tetraphosphine . For example, a commercial operation in which an existing rhodium-TPP catalyst solution is aging but may still meet production goals may choose to remove a portion of the catalyst (eg, 50% of the process fluid) and then add some fresh rhodium and tetraphosphine. Although such an implementation would require some PMR costs for a portion of the process fluid being removed, the process of the invention would be active, more selective than the original rhodium-TPP catalyst, and reliable.

In one embodiment, the catalyst includes rhodium, triphenylphosphine (eg, 2-4 wt.%) and one or more equivalents of tetraphosphine. For example, a commercial rhodium-TPP plant in which the catalyst solution has reached the end of its life due to internal deactivation may elect to dump all existing process fluid and charge fresh catalyst consisting of 2-4 wt.% rhodium. % triphenylphosphine and one or more tetraphosphine equivalents. This method will be active, reliable and provide higher selectivity for linear aldehyde than the original rhodium-TPP catalyst. And although the rhodium in the original process liquid will need to be recovered, the implementation of the method according to the invention will not require extensive cleaning of the reaction system or additional process equipment.

In one embodiment, the catalyst includes rhodium, one or more equivalents of tetraphosphine and triphenylphosphine (eg, 1.5-2 wt.%). For example, in a process using a catalyst consisting of rhodium and tetraphosphine, the addition of triphenylphosphine may be chosen to reduce the decomposition of tetraphosphine. Since chelating ligands are typically expensive, reducing the use of tetraphosphine can provide significant economic benefits for an industrial scale process.

In one embodiment, the catalyst includes rhodium, one or more equivalents of tetraphosphine and monophosphine (eg, at least 1.5 wt.%). For example, in a process using a catalyst consisting of rhodium and monophosphine (ie, other than TPP), the addition of tetraphosphine may be chosen to increase N:I.

Certain embodiments of the invention will now be described in more detail in the following Examples.

Examples

All parts and percentages in the following examples are by weight unless otherwise noted. The concentration of ligand A is expressed in equivalents per mole of ligand A per mole of rhodium. Pressures in the following examples are given in pounds per square inch unless otherwise noted. All manipulations, such as preparing catalyst solutions, are performed in an inert atmosphere unless otherwise specified. Comparative experiments are not embodiments of the invention.

The gas composition (mol %) is measured using gas chromatography (GC) and then partial pressures are calculated from the total pressure using Raoult's law.

The concentration of free tetradentate phosphine is measured using High Performance Liquid Chromatography (HPLC). To prevent oxidation during analysis, phosphines are converted to stable phosphine sulfides by mixing with a sulfur-rich diluent (50:50 v/v acetonitrile:THF, elemental sulfur-saturated).

External standard HPLC analysis is performed on an Agilent 1200 Infinity Series LC equipped with an SB-C8 3.0 mm UHPLC, 1.8 µm guard column, followed by a Zorbax SB-C8 analytical column (3.0 x 150 mm). The solvent gradient is 55% water with the remainder of acetonitrile over 4 minutes; then adjusted to 20:80 water:acetonitrile for 22 minutes and finally returned to the original composition for the remainder of the 35-minute run. The solvent flow rate was 1.00 mL/min while maintaining the column temperature at 40°C. Two microliters of sample are injected into the system; the multi-wavelength UV detector is set at 240 nm.

Preparation of Ligand A

In these examples, the tetradentate phosphine compound Ligand A is used and prepared as follows.

Synthesis of 1,1'-biphenyl-2-2',6,6'-tetracarboxylic acid. A 5 L jacketed reactor equipped with an overhead stirrer, a bottom drain valve and a water condenser is charged with 1 L of methylene chloride and 50 g (0.247 mol) of pyrene. The mixture is stirred until the pyrene dissolves, after which 0.25 L of acetonitrile, 1.5 L of deionized water and 2.0 g of ruthenium (III) chloride are added. The resulting two-phase mixture is intensively stirred and cooled to 18°C by circulating coolant through the jacket. Then I add sodium periodate (total 500 g; 2.34 mol) in small portions over 2.5 hours, maintaining the temperature in the reactor at 23-27°C. The reaction mixture, initially brown, quickly turns dark brown and finally brownish green. After stirring overnight (18 hours), stop stirring and allow the layers to separate. The bottom layer is poured into a Buchner funnel to collect the crude green/brown solid, which is washed with methylene chloride (2 x 500 ml) and filter-dried with air. The solid is then returned to the reactor and boiled with 1.5 L of acetone for 1 hour. After cooling to room temperature, the yellow solution is poured into a Buchner funnel and the filtrate is concentrated on a rotary evaporator to obtain a yellow solid. The crude tetraacid product is dried in a vacuum oven at 70°C overnight and used without further purification.

Synthesis of 1,1'-biphenyl-2,2',6,6'-tetramethanol. The 5 L reactor used in the previous step is dried and purged with nitrogen overnight. Crude 1,1'-biphenyl-2-2',6,6'-tetracarboxylic acid (50.0 g, 0.152 mol) was charged along with 1.5 L of THF under nitrogen. The resulting solution is stirred and cooled to 0°C by circulating the cooled liquid through the reactor jacket. A solution of lithium aluminum hydride in THF (1M; 666 mL; 0.665 mol) was then added via a peristaltic pump over 2 hours. During this time, the mixture is intensively stirred and the temperature in the reactor is maintained at 0-2°C; For safety reasons, the reactor is slowly purged with nitrogen, and the effluent is passed through a condenser to purge the reactor of evolved hydrogen. After addition of lithium aluminum hydride is complete, the reactor is cold stirred for an additional 15 minutes, then allowed to slowly warm to room temperature. After stirring at room temperature for 30 minutes, the reactor contents are heated to 65°C and stirred overnight while slowly purging with nitrogen. The next morning, the reactor is cooled to 0°C and quenched with 25 ml of water added slowly through a peristaltic pump, then 50 ml of 10% NaOH and 75 ml of water at 0 – 7°C for 1.5 hours. During quenching, hydrogen is released, so quenching is carried out with nitrogen purging. The quenched solution is allowed to slowly warm to room temperature and then drained from the reactor into a Buchner funnel. The solids thus collected are washed with hot THF (3 x 300 ml). Volatiles were removed from the combined filtrate on a rotary evaporator to give 35 g of a light yellow solid. The solids were dissolved in hot ethanol, filtered and the solvent was removed on a rotary evaporator. After drying overnight in a vacuum oven, 32.3 g of light yellow product remained (77.1% yield, about 97% purity). ¹ H NMR (400 MHz, DMSO). δ 7.46 (d, J = 6.8 Hz, 4H), 7.39 (dd, J = 8.6, 6.4 Hz, 2H), 4.99 (t, J = 5.3 Hz, 4H), 3.94 (d, J = 5.3 Hz, 8H) ppm. ¹³ C NMR (400 MHz, DMSO) δ 139.3, 133.1, 127.3, 125.4, 60.4 ppm.

Synthesis of 2,2'6,6'-tetrakis(chloromethyl)-1,1'-biphenyl. The 5 liter reactor was dried and purged with nitrogen overnight and then charged with 1,1'-biphenyl-2,2',6,6'-tetramethanol (45 g, 0.164 mol), methylene chloride (450 ml) and dimethylformamide (1 ml). The resulting yellow solution is stirred and cooled to 0°C. Thionyl chloride (1071 g, 9.01 mol) was then added slowly via a peristaltic pump over 2 hours, maintaining the reactor temperature at approximately 0°C; During addition, the reactor is purged with nitrogen to remove the HCl and SO ₂ formed, while the off-gases are passed through a water scrubber. The reaction solution is then allowed to warm to room temperature and stirred for 30 minutes before refluxing (approx. 45°C) overnight. The next day, the solution was cooled to 15°C and discharged from the reactor. Methylene chloride was removed by atmospheric distillation, and residual thionyl chloride was removed by vacuum distillation. The resulting residue was first dried on a rotary evaporator and then dried in a vacuum oven at 60°C overnight to obtain 58.1 g of a yellow solid. (Yield 100%, purity approx. 95%). ^1H NMR (400 MHz CDCl2) δ 7.66-7.60 (m, 4H), 7.56 (dd, J=8.8, 6.4 Hz, 2H), 4.28 (s, 8H) m.d. ¹³ C NMR (400 MHz, CDCl2) δ 136.9, 135.5, 131.3, 130.3, 45.0 ppm.

Synthesis of (biphenyl-2,2',6,6'-tetramethanediyl)tetrakis(diphenylphosphane) (Ligand A). Lithium wire (2.1 g, 300 mmol) is cut into small pieces and loaded into a 250 ml flask in a dry box along with anhydrous THF (130 ml). The suspended solution is transferred to a Schlenk line and cooled in an ice water bath under a nitrogen atmosphere. Chlorodiphenylphosphine (28.1 mL, 151.7 mmol) was added dropwise at 0°C over 50 minutes and then stirred for an additional 30 minutes at 0°C. During this time, the color changes from dull yellow to red. The solution was transferred to a dry box and stirred at room temperature overnight. The next morning, the solution was filtered through a cannula into a clean, dry 500 ml round bottom flask, transferred to a Schlenk line and cooled to -78°C. A solution of 2,2'6,6'-tetrakis(chloromethyl)-1,1'-biphenyl (12.7 g, 37 mmol) in THF (60 ml) was added dropwise over 50 minutes and then stirred while cold for another 20 minutes. The solution is then allowed to warm slowly to room temperature, then transferred to an oven and stirred overnight. Degassed methylene chloride (300 ml) and water (150 ml) were then added and the resulting mixture was allowed to separate. The bottom layer was transferred to a round bottom flask and concentrated by rotary evaporation at 30°C to give a THF solution of the crude product. While heating this solution at 65°C under a stream of nitrogen, degassed ethanol (100 ml) is slowly added. During the addition of ethanol, a white solid began to precipitate. The mixture was then allowed to cool and placed in the refrigerator overnight; the resulting solids were collected the next day by oven filtration and washed with ethanol (2 x 50 ml). Vacuum drying overnight provided the desired product as a white powder (90% yield, 99% purity). ³¹ P NMR (400 MHz, CDCl3) δ - 14.5 ppm ^1H NMR (400 MHz, CDCl3) δ 7.30-7.17 (m, 40 H), 6.91-6.82 (m, 2H), 6.72 (d, J = 7.7 Hz, 4H), 3.21 (s, 8H) ppm. Ligand A, a tetradentate phosphine, has the following structure:

Comparative Ligand B

Comparative ligand B is BISBI (neither monophosphine nor tetradentate phosphine), which is known to provide an active and selective hydroformylation catalyst. Methods for preparing BISBI and examples of its use as a hydroformylation ligand can be found, for example, in US Pat. No. 4,694,109. BISBI used in the comparative experiments below was purchased from Proactive Molecular Research of Alachua, FL and was used as received. The structure of BISBI (Ligand B) is shown in FIG. 2.

Fig. 2 Reference ligand B; BISBI.

General technique

Unless otherwise noted, examples and comparison experiments were performed in a 90 mL Fisher Porter flow reactor equipped with precise temperature and gas flow controls. The reactor off-gases are analyzed by online GC to determine partial pressures. Mixing in a flow reactor is carried out by a continuous gas flow through a bubbler at the bottom of the reactor. This reactor design is described in detail in US Pat. No. 5,731,472, the teachings of which are incorporated by reference.

Reaction rates are expressed in moles of aldehyde produced per volume of catalyst solution per unit time (mol/l-hour); this value is further divided by the propylene partial pressure to help mitigate the effects of small unavoidable variations in propylene feed rate (rate/olefin). Product selectivity is expressed as the ratio of linear (normal) aldehyde to branched (iso)aldehyde (N:I).

These examples use an accelerated testing technique, referred to herein as the blocking technique, to demonstrate the effect of the separation zone on the catalyst. This testing procedure involves exposing solubilized activated rhodium complex catalysts to low partial pressures and high temperatures for a much longer period of time than conventional continuous liquid recycle hydroformylation processes to obtain meaningful results in practice. For example, catalytic deactivation and/or ligand degradation as discussed herein, which can occur during continuous liquid recycle hydroformylation, may take weeks to quantify under conventional aldehyde distillation reduction procedures because the catalyst is only exposed to such evaporator conditions for several minutes each day, whereas accelerated testing (lockout procedure) can be completed in a matter of hours or days by continuously maintaining the reaction product fluid at high aldehyde recovery type distillation temperatures for an extended period of time. Lockout segments include periods of time during which the reactor is sealed under reduced pressure and high temperatures. This technique is designed to simulate the effect of the separation zone on the catalyst solution.

Comparative Experiment A

The reactor was charged with tetraglyme (20 ml), rhodium (200 ppm) and Ligand A (1.5 equivalents). Hydroformylation is carried out at a CO pressure of 20 psig. inch, H ₂ 50 psi inch and propylene 20 psi. inch at 90°C and the basal rates of hydroformylation and N:I are measured. After running overnight, the reactor was sampled for HPLC to determine Ligand A concentration and then blocked at 10 psi. inch and 115°C overnight. After blocking in the segment, hydroformylation is reinitiated under initial conditions and the catalyst solution is collected for HPLC; then the blocking in the technique is repeated a second time.

Comparative Experiment B

The procedure for Comparative Experiment A is repeated except for the amount of Ligand A added (5 equivalents are used for this experiment).

Examples 1-4

The procedures of Comparative Experiment A and B were repeated except for the addition of triphenylphosphine (TPP) (5 or 10 wt%).

The results of Comparative Experiment A and B and Examples 1-4 are shown in Tables 1 and 2.

Table 1

TFF Ligand A Initial after the 1st blocking in after the 2nd blocking in wt.% Equiv. speed N:I speed N:I speed N:I C.E.A 0 1.5 0.1254 42.7 0.0164 23.0 0.0119 18.0 C.E.B 0 5.0 0.1303 40.2 0.0337 27.7 0.0245 25.9 Etc. 1 5 1.5 0.0308 19.3 0.0256 17.4 0.0240 16.4 Etc. 2 5 5.0 0.0278 27.7 0.0274 26.9 0.0280 26.2 Etc. 3 10 1.5 0.0215 14.3 0.0198 13.0 0.0187 13.2 Etc. 4 10 5.0 0.0167 23.2 0.0165 23.7 0.0169 22.2

Table 2. BDL = Below Detection Limit.

Ligand A wt.% according to HPLC data elementary After the 1st blocking in After the 2nd blocking in C.E.A 0.0644 0.0087 BDL C.E.B 0.4675 0.3438 0.3204 Etc. 1 0.1135 0.0969 0.0836 Etc. 2 0.5353 0.5372 0.5118 Etc. 3 0.1244 0.1239 0.1072 Etc. 4 0.5243 0.5399 0.5162

Both the hydroformylation rate and N:I demonstrated by catalyst solutions consisting only of rhodium and Ligand A (Comparative Experiments A and B) drop significantly after blocking in the procedures. The rates after blocking are suggestive of the activity that the catalyst solutions of Comparative Experiments A and B will exhibit during long-term continuous operation. In contrast, the initial hydroformylation rates are lower in Examples 1-4, but the catalyst solutions in these embodiments demonstrate the ability to remain active after being blocked for certain periods, indicating increased stability during long-term continuous operation. In addition, the catalyst solutions of the present invention reduce the degradation of Ligand A. Since chelating ligands are generally expensive, reducing the consumption of Ligand A would improve the economics of the process.

Comparative experiments C, D

The procedure for Comparative Experiments A and B was repeated except that Comparative Ligand B was used instead of Ligand A.

Comparative experiments E-H

The procedure of Examples 1-4 is repeated except using Comparative Ligand B instead of Ligand A.

The results of the C-H comparison experiments are shown in Table 3.

Table 3

TFF Compare
Ligand B Initial after the 1st blocking in after the 2nd blocking in wt.% (equivalent) speed N:I speed N:I speed N:I S.E. C 0 1.5 0.0667 27.5 0.0143 1.8 0.0010 2.0 S.E. D 0 5.0 0.0640 35.8 0.0162 15.3 0.0127 18.2 S.E. E 5 1.5 0.0333 6.6 0.0261 5.9 0.0271 5.5 S.E. F 5 5.0 0.0218 10.7 0.0204 10.6 0.0192 10.0 S.E. G 10 1.5 0.0260 7.3 0.0229 7.0 0.0215 7.0 S.E. H 10 5.0 0.0175 8.9 0.0165 9.4 0.0161 9.0

It should be noted that catalysts consisting of only rhodium and Comparative Ligand B are negatively affected by the blocking period in terms of both catalyst deactivation and N:I. Although catalyst solutions consisting of rhodium, TPP and Comparative Ligand B also showed improved stability with respect to rate and N:I degradation, they did not exhibit an N:I greater than 11. Without being limited by theory, this low N:I suggests that the catalyst rhodium-Comparative ligand B is more easily inhibited by TPP, and thus the resulting mixture of active complexes contains a relatively small amount of the active and selective rhodium-BISBI complex.

Examples 5-10

Each of the six reactors is charged with tetraglyme (20 ml), rhodium (200 ppm), Ligand A (1.5 or 3 equivalents) and TPP (3 - 5 wt.%). Hydroformylation is carried out at a CO pressure of 20 psig. inch, H ₂ 50 psi inch and propylene 20 psi. inch at 90°C and the basal rates of hydroformylation and N:I are measured. The reactors are blocked twice at 10 psi and 115°C overnight; After each block in the segment, the characteristics of the catalyst are determined under initial conditions and before blasting. Additional Ligand A (one equivalent) is then added to each reactor and the resulting change in performance is measured. The summarized results are presented in Table 4.

Table 4

TFF Ligand A Initial After the 1st blocking in After the 2nd blocking in After additional Ligand A wt.% eq Speed N:I Speed N:I Speed N:I Speed N:I Etc. 5 3 1.5 0.0385 23.6 0.0278 18.7 0.0250 17.2 0.0282 24.0 Etc. 6 3 3.0 0.0390 29.0 0.0330 26.6 0.0290 25.8 0.0312 28.0 Etc. 7 4 1.5 0.0315 21.4 0.0275 18.7 0.0260 17.8 0.0276 24.0 Etc. 8 4 3.0 0.0305 26.6 0.0293 25.8 0.0281 25.1 0.0288 27.2 Etc. 9 5 1.5 0.0278 18.5 0.0257 17.0 0.0250 16.3 0.0242 21.5 Etc. 10 5 3.0 0.0258 24.4 0.0275 23.0 0.0234 22.6 0.0236 24.3

It should be noted that the initial rate of hydroformylation is inversely proportional to the concentration of TPP and that N:I is directly proportional to the concentration of Ligand A; in addition, the ability to increase N:I by adding more Ligand A towards the end of the experiment is demonstrated. Without being bound by theory, this suggests that the observed catalysis is the result of a mixture of active rhodium complexes, and that, in addition, some rhodium exists in a relatively inactive form, probably a rhodium triphosphoride complex consisting of Ligand A and TPP.

Additionally, it is noted that the effect of blocking periods is less significant in solutions containing 4 to 5 wt.% TPP, suggesting that a catalyst consisting of rhodium and 4-5 wt.% TPP will offer an active, selective and reliable option.

Example 11

The reactor is charged with tetraglyme (20 ml), rhodium (200 ppm) and TPP (12 wt.%). Hydroformylation is carried out at a CO pressure of 50 psig. inch, H ₂ 50 psi inch and propylene 8 psi. inch at 90°C and measure basal rates of hydroformylation and N:I. Ligand A (3 equivalents to rhodium) is then added and the resulting characteristics determined. Partial pressure changes are then made (decreasing CO, increasing H ₂ ) to measure the effect on catalysis. The reactor is then blocked twice at 110°C and a total pressure of 10 psig. inch overnight. Capacity is determined after each block in the segment under the same partial pressure and temperature conditions that were set before the block began.

Example 12

The procedure of Example 11 was followed except for the amount of TPP (6 wt.%) loaded into the reactor.

The results for Examples 11 and 12 are shown in Table 5.

Table 5

Etc. TFF (wt.%) Rh-TFF only Addition of Ligand A after the 1st blocking in after the 2nd blocking in Initial 50 CO: 50
H2: 8 C3 20 CO: 74
H2: 7 C3 speed N:I speed N:I speed N:I speed N:I speed N:I eleven 12 0.0250 4.2 0.0140 11.2 0.0125 16.3 0.0141 17.0 0.0135 16.9 12 6 0.0353 3.3 0.0225 14.7 0.0232 21.2 0.0228 20.9 0.0229 20.3

The results of Example 11 represent an embodiment in which the N:I demonstrated by a catalyst consisting of rhodium and TPP at concentrations typically used in commercial processes can be increased by the addition of Ligand A. While the hydroformylation rate of Example 11 is reduced slightly after the addition of Ligand A, the catalyst solution of the invention still retains >50% of the original activity of the rhodium-TPP catalyst, and in addition it tolerates the blocking period quite well. Thus, Example 11 is expected to provide a robust and selective implementation of the continuous process.

The results of Example 12 show that the option in which half of the catalyst solution in the industrial process is removed and then Ligand A is added will result in a higher N:I, as well as a higher hydroformylation rate, than the option presented in Example 11.

Example 13

The reactor is charged with tetraglyme (20 ml), rhodium (340 ppm) and tris(o-tolyl)phosphine (4 wt.%). Hydroformylation is carried out at a CO pressure of 10 psi. inch, H ₂ 50 psi inch and propylene 20 psi. inch at 90°C and the basal rates of hydroformylation and N:I are measured. Ligand A (4 equivalents to rhodium) is then added and the resulting characteristics determined.

Example 14

The procedure of Example 13 is followed except for the use of tribenzylphosphine instead of tris(o-tolyl)phosphine.

Example 15

The procedure of Example 13 is followed except for the use of cyclohexyldiphenylphosphine instead of tris(o-tolyl)phosphine.

The results of Examples 13-15 are shown in Table 6.

Table 6

Monophosphine only Addition of Ligand A Etc. speed/olefin N:I speed/olefin N:I 13 0.0228 0.9 0.0658 24.0 14 0.2000 1.9 0.0856 21.9 15 0.0436 1.7 0.0557 18.1

The results of Table 6 demonstrate embodiments of the present invention with various monophosphines.

Claims (19)

1. A catalyst composition for a hydroformylation method, containing: (a) a transition metal being rhodium; (b) monophosphine; And (c) tetraphosphine having the following structure: wherein each P is a phosphorus atom and each of R ¹ -R ⁴⁶ is independently hydrogen, a C1-C8 alkyl group, an aryl group, an alkaryl group, an alkoxy group, a haloalkyl group, a haloaryl group or a halogen and wherein the catalyst composition contains at least 40 moles of monophosphine per mole of transition metal. 2. The catalyst composition according to claim 1, characterized in that the monophosphine is one or more of the following components: triphenylphosphine, tris(o-tolyl)phosphine, trinaphthylphosphine, tri(p-methoxyphenyl)phosphine, tri(m-chlorophenyl)phosphine , tribenzylphosphine, tricyclohexylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine and trioctylphosphine. 3. The catalyst composition according to claim 1 or 2, characterized in that the monophosphine is triphenylphosphine. 4. The catalyst composition according to claim 1 or 2, characterized in that each of R ¹ -R ⁴⁶ represents hydrogen. 5. Hydroformylation method, including: contacting an olefin, hydrogen and carbon monoxide in the presence of a catalyst in a reaction liquid in a reactor, wherein the catalyst contains: (a) a transition metal being rhodium; (b) monophosphine; And (c) tetraphosphine having the following structure: wherein each P represents a phosphorus atom and each of R ¹ -R ⁴⁶ independently represents hydrogen, a C1-C8 alkyl group, aryl group, alkaryl group, alkoxy group, haloalkyl group, haloaryl group or halogen and wherein monophosphine is present in the reaction liquid in the reactor in an amount greater than or equal to 1.5 wt.% of the total weight of the reaction liquid in the reactor. 6. The method according to claim 5, characterized in that the monophosphine is triphenylphosphine. 7. The method according to claim 5, characterized in that each of R ¹ -R ⁴⁶ represents hydrogen. 8. The method according to claim 5, characterized in that the olefin is propylene.