RU2795878C2 - Methods for slowing catalyst deactivation and/or slowing tetraphosphin ligand consumption in hydroformylation processes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: inventions relate to methods for slowing down the deactivation of a catalyst and slowing down the consumption of a tetraphosphine ligand in a hydroformylation process. A method for slowing down catalyst deactivation in a hydroformylation process and a method for slowing down the consumption of a tetraphosphine ligand in a hydroformylation process are described, comprising (a) contacting an olefin with carbon monoxide, hydrogen, and a catalyst containing (A) a transition metal in which the transition metal contains rhodium, (B) tetraphosphine having the following structure:

where each P represents a phosphorus atom, and each of R1-R46 independently represents hydrogen, C1-C8 alkyl group, aryl group, alkaryl group or halogen, and the said contacting is carried out in one or more reaction zones and under hydroformylation conditions; and (b) adding to the reaction zone a monophosphine having the following structure:

where P represents a phosphorus atom, and each of Y1-Y3 independently represents an aryl group, an alkaryl group, a cycloalkyl group, a benzyl group, a C3-C8 alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen.

EFFECT: slowing down the deactivation of the catalyst and slowing down the consumption of tetraphosphine ligand in the process of hydroformylation.

11 cl, 5 tbl, 11 ex

Description

Technical field

This invention relates to methods for slowing down catalyst deactivation and/or slowing down the consumption of tetraphosphine ligand in a hydroformylation process.

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. In this method, with a certain set of variables, in the presence of certain triorganophosphorus ligands, certain rhodium complexes are used to provide efficient catalysis of 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"). Commercial hydroformylation processes have successfully used a rhodium-TPP catalyst for decades, and a key aspect of production is the use of a large excess of TPP relative to rhodium. For example, industrial propylene hydroformylation processes are often carried out at TPP concentrations of 10-12 percent by weight based on the total weight of the reaction medium. Such high concentrations of TPP are used to achieve the required product regioselectivity and to improve catalyst stability.

Over time, hydroformylation catalysts deactivate due to a variety of reasons, including the formation of rhodium clusters or the presence of inhibitory compounds. Measures can be taken to maintain achievement of production targets, such as increasing the concentration of rhodium, raising the reaction temperature, or treating to regenerate the catalyst, as described, for example, in US patent No. 5237106. Despite such measures, the catalysts eventually reach the point when deactivation renders them unsuitable for industrial use. Such "spent" catalysts must be removed from the process, sent to noble metal recovery (PMR) and replaced with fresh batches of rhodium and ligand(s). The costs associated with PMR, full rhodium and ligand replacement, and performance degradation during catalyst replacement can be significant.

Hydroformylation processes using C3 and higher olefins provide a mixture of linear (normal) and branched (iso) aldehydes; regioselectivity is usually expressed as the ratio of normal aldehyde to isoaldehyde (N:I). It is well known that catalysts capable of producing an N:I greater than about 10-12 consist of chelating ligands containing at least two phosphorus containing moieties (see e.g. "Rhodium Catalyzed Hydroformylation", Kluwer Academic Publishers, 2000) . Specific examples include, but are not limited to, tetraphosphine ligands such as those described in US Pat. No. 7,531,698.

Such chelating ligands are usually obtained by specialized synthesis, which increases their cost. Chelating ligands are known to degrade during continuous use due to oxidation, hydrolysis, or rhodium-promoted side reactions. Since the hydroformylation rate and product regioselectivity decrease if the concentration of the chelating ligand becomes too low, it is common practice to top up these compounds periodically to maintain desired performance. The rate at which chelating ligand must be added to the system to maintain the desired concentration ("ligand consumption rate") is a key economic factor for processes using these costly compounds.

It is desirable to provide a method for slowing catalyst deactivation and/or ligand consumption rate for high N:I hydroformylation processes.

The essence of the invention

The present invention relates to slowing catalyst deactivation and/or the rate of consumption of tetraphosphine ligand in a hydroformylation process. For example, according to some embodiments, it has surprisingly been found that the addition of certain monophosphines to the reaction zone can slow down the rate of hydroformylation and/or slow down the rate of consumption of the chelating tetraphosphine ligand.

In one aspect, a method for slowing catalyst deactivation and/or slowing tetraphosphine ligand consumption in a hydroformylation process comprises:

(a) contacting the olefin with carbon monoxide, hydrogen and a catalyst containing (A) a transition metal; (B) 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, or a halogen, and optionally (C) a monophosphine having the following structure:

where P is a phosphorus atom and each of Y1-Y3 is independently an aryl group, an alkaryl group, a cycloalkyl group, a C3-C8 benzyl group, an alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen, and bringing into contact is carried out in one or more reaction zones and under hydroformylation conditions; And

(b) adding to the reaction zone an additional amount of monophosphine having the above structure. In some embodiments, the transition metal is rhodium and the monophosphine is triphenylphosphine.

These and other implementation options are described in more detail in the following detailed description of the invention.

Detailed description

All references to the Periodic Table of the Elements and the various groups of said table refer to the version published in CRC Handbook of Chemistry and Physics, 72nd ed. (1991-1992) CRC Press, on p. I-11.

Unless otherwise indicated, it does not follow from the context, all parts and percentages are expressed by weight, and all test methods are current at the date of filing of this application. In the context of U.S. patenting practice, the contents of any patents, patent applications, or publications referred to are incorporated by reference in their entirety (or their U.S. equivalent version is incorporated in the same way by reference), especially with respect to the description of definitions (to the extent that they are not contrary to the definitions specifically given in this description) and common knowledge in the art.

In this context, the terms in the singular, "at least one" and "one or more" are used interchangeably. The terms "comprises", "includes" and variations thereof are not intended to be limiting if these terms appear in the specification and claims.

Also in this context, specifying numeric ranges using endpoints includes all values within a given range (for example, from 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. .d.). In the context of this invention, it should be understood, in accordance with the general knowledge of experts in the art, that the numerical range includes and covers all possible subranges that are included in this range. For example, the range 1 to 100 includes 1.01 to 100, 1 to 99.99, 1.01 to 99.99, 40 to 60, 1 to 55, and so on. In addition, in this context, the indication of numerical ranges and/or numerical values, including such indications in the claims, can be read as including the term "about". In such cases, the term "about" refers to numerical ranges and/or numerical values that are essentially the same as those specified herein.

In this context, “m.d. wt." means parts per million by weight.

In the context of this invention, the term "hydrocarbon" includes all valid compounds containing at least one hydrogen atom and one carbon atom. Such valid compounds may also contain one or more heteroatoms. In a broad aspect, 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.

In this context, the term "substituted" includes all acceptable substituents of organic compounds, unless otherwise indicated. In a broad aspect, acceptable substituents include acyclic and cyclic, branched and straight, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. Illustrative substituents include, for example, alkyl, alkyloxy, aryl, aryloxy, hydroxyalkyl, aminoalkyl, in which the number of carbon atoms can be from 1 to 20 or more, preferably from 1 to 12, as well as hydroxy, halogen and amino. Allowed substituents may be one or more, and they may be the same or different for the respective organic compounds. This description is in no way limited to the allowable substituents of organic compounds.

As used herein, the term "hydroformylation" includes, but is not limited to, all hydroformylation processes that involve the conversion of one or more substituted or unsubstituted olefin compounds, or a reaction mixture containing one or more substituted or unsubstituted olefin compounds, to one or more substituted or unsubstituted aldehydes or into a reaction mixture containing one or more substituted or unsubstituted aldehydes. Aldehydes can be asymmetric or non-symmetrical.

The terms "ligand degradation" and "ligand degradation" are used interchangeably and include the chemical conversion of monophosphine or tetraphosphine loaded into the reaction medium.

The term "tetraphosphine ligand consumption" includes the amount of tetraphosphine consumed during the hydroformylation process (eg, as a result of ligand degradation) over time. For example, by taking into account the amount of tetraphosphine added to the hydroformylation process and periodically measuring the concentration of tetraphosphine in the reaction medium (by the HPLC method described in the Examples section below), the amount of tetraphosphine consumed in this process can be calculated.

The terms "deactivation" and "deactivation of the catalyst" are used interchangeably and include the reduction in the rate of hydroformylation over time. Those skilled in the art will appreciate that the rate of hydroformylation can be determined by various techniques. For example, the hydroformylation rate can be determined by making at least two measurements under comparable process conditions (eg, the same rhodium concentration, reaction temperature, gas partial pressures, etc.) over a period of time. For example, the rate of aldehyde formation is routinely measured (eg, in pounds of product per hour, measured by determining the aldehyde content of the constant rate reactor effluent by gas chromatography) under comparable process conditions over several weeks. A decrease in the amount of aldehyde formed means catalyst deactivation.

The terms "reaction fluid", "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 triphenylphosphine complex catalyst), (b) tetraphosphine transition metal catalyst (e.g. rhodium tetraphosphine complex catalyst), (c) free monophosphine (e.g. triphenylphosphine), (d) free tetraphosphine, (e) aldehyde products resulting from the reaction, (f) unreacted reactants, (g) solvent for said transition metal complex catalysts and said free phosphine ligands, and optionally (h) degradation products of monophosphine ligand and tetraphosphine ligand. The reaction medium may include, but is not limited to, (a) fluid in the reaction zone, (b) fluid flow on the way to the recovery zone, (c) fluid in the recovery zone, (d) return flow, (e) fluid effluent from the reaction or isolation zone, (f) fluid in an external cooler, and (g) ligand degradation products.

The term "ligand degradation products" includes, 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 medium. 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 cleavage side reactions. It is also contemplated that the degradation products of the ligand include alkyldiarylphosphines, which are known to be present in hydroformylation catalyst solutions based on a rhodium triarylphosphine complex (see, for example, US Pat. No. 4,297,239, Col. 5). It is further contemplated that ligand degradation products include any and all compounds that result from the oxidation of phosphine moieties. For example, ligand degradation products may include phosphine oxides formed from monophosphine introduced into the process, from the partial or complete oxidation of tetraphosphine introduced into the process, or from the oxidation of phosphine compounds formed from rhodium-promoted side reactions (e.g., oxidation of triphosphine compounds formed from the starting tetraphosphine).

In this context, the terms "tetradentate phosphine" and "tetraphosphine" are used interchangeably and include compounds containing four phosphine atoms, each of which is associated with three carbon atoms.

In this context, the terms "monodentate phosphine" and "monophosphine" are used interchangeably and include compounds that contain one phosphine atom bonded to three carbon atoms.

In this context, the terms "rhodium complex", "rhodium complex catalyst" and "catalyst complex" are used interchangeably and include at least one rhodium atom with ligands linked or coordinated by 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 includes monophosphine or tetraphosphine molecules that are not bound or coordinated to rhodium.

In general, this invention relates to methods for slowing down catalyst deactivation and/or slowing down the consumption of tetraphosphine ligand in a hydroformylation process. The catalyst contains a transition metal (eg rhodium) and a tetraphosphine ligand.

In one aspect, a method for slowing catalyst deactivation and/or slowing tetraphosphine ligand consumption in a hydroformylation process comprises:

(a) contacting the olefin with carbon monoxide, hydrogen and a catalyst containing (A) a transition metal; (B) 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, or a halogen, and optionally (C) a monophosphine having the following structure:

where P is a phosphorus atom and each of Y1-Y3 is independently an aryl group, an alkaryl group, a cycloalkyl group, a C3-C8 benzyl group, an alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen, and bringing into contact is carried out in one or more reaction zones and under hydroformylation conditions; And

(b) adding to the reaction zone an additional amount of monophosphine having the above structure. In some embodiments, the transition metal contains rhodium. In some embodiments, the olefin is propylene. In some embodiments, the amount of added monophosphine is at least 40 moles of phosphine per mole of transition metal. In some embodiments, the amount of monophosphine added to the reaction zone is greater than 1.5 percent by weight relative to the reaction medium in the reaction zone, based on the total weight of the reaction medium in the reaction zone.

In some embodiments, the monophosphine 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 ionophosphine is triphenylphosphine. In some embodiments, the monophosphine is a bulk monophosphine. In some embodiments, the proposed catalyst contains a mixture of different types of monophosphines.

In some embodiments, each of R1-R46 in the tetraphosphine structure is hydrogen. In some embodiments, the catalyst contains one or more of the following tetraphosphines:

In some embodiments, the transition metal contains rhodium, the monophosphine is triphenylphosphine, each of R1-R46 is hydrogen, and the olefin contains propylene.

In some embodiments, the decrease in hydroformylation rate over time is less than in a process performed under the same conditions but without monophosphine. In some embodiments, the consumption rate of tetraphosphine ligand in the hydroformylation process is lower than in the hydroformylation process carried out under the same conditions but without monophosphine.

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

Syngas is the name of a gas mixture that contains varying amounts of CO and H2. Methods for its preparation are well known. Hydrogen and CO are usually the main components of synthesis gas, but synthesis gas may contain CO2 and inert gases such as N2 and Ar. The molar ratio of H2 to CO varies greatly, but is usually 1:100 to 100:1 and preferably 1:10 to 10:1. Synthesis gas is commercially available and is often used as a source of fuel or as an intermediate in the production of other chemical compounds. The most preferred H2:CO molar ratio for chemical production is 3:1 to 1:3, and typically 1:2 to 2:1 is required for most hydroformylation processes. Syngas mixtures are the preferred source of hydrogen and CO.

The olefinic feedstocks that can be used in the hydroformylation reactions of this invention may be terminally or internally unsaturated, and may be straight, branched or cyclic in structure. Such olefins may contain from 2 to 20 carbon atoms and may contain one or more ethylenically unsaturated groups. In addition, such olefins may contain groups or substituents that do not significantly adversely affect the hydroformylation process, such as carbonyl, carbonyloxy, hydroxy, hydroxy, oxycarbonyl, halogen, alkoxy, aryl, alkyl, haloalkyl, and the like. Exemplary olefinically unsaturated compounds include alpha-olefins, internal olefins, alkyl alkenoates, alkenyl alkanoates, alkenyl alkyl ethers, alkenols, and the like, e.g., 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, and the like. Of course, it should be understood that mixtures of different olefinic feedstocks can be used if desired. Embodiments of this invention may be particularly suitable for hydroformylation of C3 and higher olefins. Thus, in some embodiments, the olefinically 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 such as alpha-olefins and internal olefins.

The hydroformylation process advantageously uses a solvent. You can use any suitable solvent that does not interfere with the hydroformylation process. By way of illustration, suitable solvents for rhodium catalyzed hydroformylation processes include those described in, for example, US Pat. Nos. 3,527,809; 4148830; 5312996; and 5,929,289. Non-limiting examples of suitable solvents include saturated hydrocarbons (alkanes), aromatic hydrocarbons, ethers, aldehydes, ketones, nitriles, alcohols, esters, and aldehyde condensates. 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 saturation limit. Illustrative 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 product aldehydes to be produced and/or higher boiling liquid aldehyde condensation by-products, for example, which may be formed in situ during the hydroformylation process, as described in, for example, US 4,148,830 and US 4,247,486. The basic solvent typically ends up containing both aldehyde products and higher boiling liquid aldehyde condensation by-products ("heavy compounds") 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 about 5 percent to about 95 percent by weight based on the total weight of the reaction medium. Mixtures of solvents may be used.

The catalyst used in the methods of this invention contains a transition metal and tetraphosphine. In some particularly suitable embodiments, the catalyst contains rhodium and tetraphosphine. The most suitable catalyst does not contain metal-bound halogens such as chlorine and contains hydrogen, carbon monoxide and tetraphosphine complexed with rhodium metal to form a catalyst soluble in the aforementioned liquid phase and stable under the reaction conditions.

The transition 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, and the preferred metals are rhodium, cobalt, iridium and ruthenium, more preferably rhodium, cobalt and ruthenium, especially rhodium.

The number of available coordination centers for such metals is known in the art. Thus, catalytic particles, which may contain a mixture of complex catalysts, may contain monomeric, dimeric, or higher order forms of nuclearity, which are preferably characterized by at least one complexed organophosphine-containing molecule per molecule of metal, for example, rhodium. For example, it is envisaged that the catalyst particles of the preferred catalyst used in the hydroformylation reaction may be complexed with carbon monoxide and hydrogen, in addition to organophosphine ligands, considering the use of carbon monoxide and hydrogen gas in the hydroformylation reaction.

In some preferred embodiments, the transition metal is rhodium. Rhodium can be introduced into the liquid phase in the form of a preformed catalyst, for example a stable crystalline solid, rhodium hydridocarbonyl-tris(triphenylphosphine), RhH(CO)(PPh3)3. Rhodium can be introduced into the liquid medium in the form of a precursor which is converted in situ to a catalyst. Examples of such a precursor form are rhodium carbonyl triphenylphosphine acetylacetonate, Rh2O3, Rh4(CO)12, Rh6(CO)16, and rhodium dicarbonyl acetylacetonate. Both catalyst compounds that provide 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 optimum concentration of catalyst depends on the concentration of the alpha-olefin, such as propylene. For example, the higher the propylene concentration, the generally lower the catalyst concentration required to achieve the desired conversion to aldehyde products in a reactor of a given size. Given that partial pressures and concentrations are related, using a higher partial pressure of propylene results in an increase in the proportion of propylene in the "off-gas" from the liquid medium. Since it may be necessary to purge a portion of the gas stream from the product recovery zone before returning to the liquid medium to remove some of the propane that may be present, the higher the propylene content in the "off-gas", the more propylene is lost to the propane purge stream. Thus, the economic value of propylene losses in the propane purge stream must be balanced against the capital savings associated with lower catalyst concentration.

The rhodium complex catalysts may be in homogeneous or heterogeneous form. For example, catalysts based on a complex of rhodium with a hydridocarbonylphosphine ligand can be preformed and introduced into the hydroformylation reaction mixture. More preferably, rhodium phosphine ligand catalysts can be prepared from a rhodium catalyst precursor that can be introduced into the reaction mixture to form an active catalyst in situ. For example, rhodium catalyst precursors such as rhodium dicarbonyl acetylacetonate, Rh2O3, Rh4(CO)12, Rh6(CO)16, Rh(NO3)3, etc. can be added to the reaction mixture along with tetraphosphine for in situ formation of an active catalyst. In a preferred embodiment, rhodium dicarbonyl acetylacetonate is used as the rhodium precursor and is combined in a solvent with tetraphosphine and injected into the reactor along with synthesis gas to form an active catalyst in situ. Additional tetraphosphine may be added as needed to achieve and maintain desired concentrations. In any event, it is sufficient that carbon monoxide, hydrogen, and tetraphosphine are metal-complexing ligands and that an active metal-ligand complex catalyst be present in the reaction mixture under the conditions used for the hydroformylation reaction.

In some embodiments, the catalyst composition is prepared in a mixing tank by combining a rhodium catalyst precursor with tetraphosphine.

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

The amount of tetraphosphine in the catalyst composition (completely made in a mixing tank or made 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 (completely made in a mixing tank or made in a reactor) is from 1 to 10 moles of tetraphosphine per mole of transition metal (rhodium). The number of moles of tetraphosphine is measured by high performance liquid chromatography (HPLC) as described in the Examples section. The number of moles of rhodium is measured by atomic absorption.

For commercial operation, ligand concentrations must be maintained by intermittent or continuous addition. To do this, the concentration of the ligand in the reaction mixture is regularly measured by one or more analytical methods; generally preferred is high performance liquid chromatography (HPLC). Unless otherwise indicated in this context, when mentioning the amount of ligand in the reaction mixture, the concentration of the ligand is determined using HPLC, as described in the "Examples" section. Ligand concentrations in such assays are often reported as weight percent; since it is often convenient to use it in such units in continuous operation. In some embodiments, the amount of tetraphosphine in the reaction medium in the hydroformylation process reactor is greater than or equal to 0.06 percent by weight relative to the total weight of the reaction medium in the reactor. In some embodiments, the amount of tetraphosphine in the reaction medium in the reactor of the hydroformylation process is from 0.1 to 9 percent by weight relative to the total weight of the reaction medium in the reactor. In some embodiments, if each of R1-R46 in the tetraphosphine depicted above is hydrogen, then the amount of tetraphosphine in the reaction medium in the hydroformylation process reactor is 0.1 to 4 percent by weight relative to the total weight of the reaction medium in the reactor.

By way of illustration, a preferred catalyst precursor composition consists essentially of a solubilized rhodium complex precursor, tetraphosphine and a solvent. Tetraphosphine easily displaces one of the carbonyl ligands in the acetylacetonate rhodium precursor complex, as evidenced by the evolution of gaseous carbon monoxide. After introducing the catalyst precursor composition into the reactor, additional tetraphosphine may then optionally be added to achieve the desired concentrations in the reaction medium.

Accordingly, the rhodium-ligand complex catalysts in the reaction medium of the hydroformylation reactor predominantly contain rhodium complexed with carbon monoxide and tetraphosphine. In one embodiment, mixtures of rhodium and ligand complexes are used. For example, the catalyst further comprises rhodium complexed with carbon monoxide and tetraphosphine in a chelate and/or non-chelate manner.

In addition to the rhodium complex catalyst, free monophosphine (i.e., monophosphine not complexed with the metal) may also be present in the reaction medium, and may also be present in the catalyst composition prior to introduction into the reactor, depending on the particular composition. The value of free ligand is described in US 3527809, GB 1338225 and Brown et al., supra., pages 2759 and 2761. In some embodiments, the hydroformylation process of this invention may include from 1 weight percent or more free monophosphine in the reaction medium. The reaction medium 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.

Tetraphosphine compounds that can serve as ligands according to embodiments of this invention are compounds of formula I:

where each P is a phosphorus atom and each of R1-R46 is independently hydrogen, a C1-C8 alkyl group, an aryl group, an alkaryl group, a haloalkyl group, or a halogen. In a preferred embodiment, each of R1-R46 is hydrogen. Other examples of tetraphosphines that can be used in some embodiments are described elsewhere in this specification.

In some embodiments, mixtures of tetraphosphines can be used.

Hydroformylation processes and operating conditions are well known. In a typical embodiment, the olefin (eg, propylene) is hydroformylated in a continuous or semi-continuous manner, wherein the product is isolated in a recovery zone and the concentrated catalyst solution is recycled to one or more reactors. The recycling process typically involves separating a portion of the liquid reaction medium containing the catalyst and aldehyde product from the hydroformylation reactor, i.e. from the reaction zone, either continuously or intermittently, and isolating the aldehyde product therefrom using a composite membrane such as that described in US 5,430,194 and US 5,681,473, or by the more conventional and preferred method of distilling it, i.e. separation by evaporation, in one or more stages at normal, reduced or elevated pressure, as appropriate, in a separate distillation zone; the non-volatile residue containing the metal catalyst is returned to the reaction zone as described, for example, in US 5288918. Vapor phase condensation of the materials and their isolation and further purification, for example by further distillation, can be carried out in any conventional way, the crude aldehyde product can be be fed for further purification and separation of isomers, if necessary, and any separated reactants, for example, olefinic feedstock and synthesis gas, can be recycled to the hydroformylation zone (reactor) by any suitable method. The separated metal catalyst containing the retentate of the described membrane separation, or the separated non-volatile residue containing the metal catalyst after the described evaporation separation, can be recycled to the hydroformylation zone (reactor) by any convenient means.

A typical hydroformylation reaction medium using a rhodium-tetraphosphine ligand complex contains at least some of the four main ingredients or components, i. an aldehyde product, a catalyst based on a complex of rhodium with tetraphosphine, a free tetraphosphine ligand and a solvent for said catalysts and said free ligands. Hydroformylation reaction mixture compositions may, and typically do, contain additional ingredients such as those specifically used in the hydroformylation process or those generated in situ during said process. Examples of such additional ingredients include unreacted olefin starting material, gaseous carbon monoxide and hydrogen and in situ formed by-products, ligand degradation products and high boiling liquid aldehyde condensation by-products, as well as other inert materials such as co-solvents or hydrocarbon additives, if used.

The hydroformylation reaction conditions used may vary. For example, the total pressure of the hydrogen gas, carbon monoxide, and feed olefin in the hydroformylation process can be from 1 to 69,000 kPa. However, in general, the process is preferably carried out at a total pressure of hydrogen gas, carbon monoxide and feed olefin less than 14000 kPa, and more preferably less than 3400 kPa. The minimum total pressure is limited mainly by the amount of reactants needed to achieve the required reaction rate. More specifically, the carbon monoxide partial pressure in the hydroformylation process is preferably 1 to 6900 kPa, and more preferably 21 to 5500 kPa, and the hydrogen partial pressure is preferably 34 to 3400 kPa, and more preferably 69 to 2100 kPa. Typically, the molar ratio of gaseous H2:CO may be from 1:10 to 100:1 or higher, and more preferably the molar ratio is from 1:10 to 10:1.

Generally, the hydroformylation process can be carried out at any suitable reaction temperature. Advantageously, the hydroformylation process is carried out at a reaction temperature from -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 stirrer reactor (CSTR), a venturi reactor, a bubble column reactor, or a slurry reactor. The optimal size and shape of the reactor depends on the type of reactor used. The reaction zone used may be a single vessel or may contain two or more separate vessels. The isolation zone used may be a single container or may contain two or more separate containers. The reaction zone(s) and the isolation zone(s) used in this invention may be in the same reactor or in different reactors. For example, reactive separation technologies such as reactive distillation and reactive membrane separation can be performed in the reaction zone(s).

The hydroformylation process, if necessary, can be carried out with the recycling of unspent starting materials. The reaction can be carried out in one reaction zone or in several reaction zones, as well as sequentially or in parallel. The reaction steps can be initiated by gradually adding one of the starting materials to the other. In addition, the reaction steps can be combined through the joint pressure of the starting materials. Starting materials can be added to each or all of the reaction zones in series. If complete conversion is undesirable or unattainable, then the starting materials can be separated from the product, for example by distillation, and then the starting materials are returned to the reaction zone.

The hydroformylation process can be carried out in a glass lined reactor, in a stainless steel reactor, or in a similar type of reaction equipment. The reaction zone may be equipped with one or more internal and/or external heat exchangers to control unwanted temperature fluctuations or to prevent possible "out of control" of the reaction temperature.

The hydroformylation process of this invention may be carried out in one or more steps or steps. The exact number of reaction steps or stages is determined by the best compromise between capital costs and achieving high selectivity, activity, life and ease of operation of the catalyst, as well as the intrinsic reactivity of the feed materials in question and the stability of the feed materials and the desired reaction product under the given reaction conditions.

In one embodiment, the hydroformylation process useful in this invention may be carried out in a multi-stage reactor such as described, for example, in US 5,728,893. Such multi-stage reactors may be configured with internal physical barriers that provide more than one theoretical reaction stage per reactor.

As described herein, the hydroformylation process partially deactivates the catalyst and/or degrades the ligand over time. In such hydroformylation processes using tetraphosphine ligands, catalyst deactivation and/or ligand degradation can advantageously be suppressed by adding monophosphine to the reaction zone (as described later herein).

Monophosphine compounds that can be added to the reaction zone according to embodiments of this invention are compounds of formula II:

where P represents a phosphorus atom, and each of Y1-Y3 independently represents an aryl group, an alkaryl group, a cycloalkyl group, a benzyl group, a C3-C8 alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen. 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 is a bulky or hindered monophosphine. In the context of this invention, a "bulky" or "hindered" ligand is a ligand with a Tolman steric parameter between 135 and 190°. For example, in certain such embodiments, each Y1-Y3 in Formula II may independently be a substituted or unsubstituted C3-C8 alkyl, a substituted or unsubstituted C5-C8 cycloalkyl group, or a substituted or unsubstituted C6-C12 aryl group. Illustrative preferred bulk monophosphines include those described in US 4,283,562 and US Pat. No. 5,741,945 (eg, col. 10, page 57 - col. 13, page 39).

In some embodiments, mixtures of monophosphines can be used.

The amount of monophosphine that can be added to the reaction zone is, in some embodiments, at least 40 moles of monophosphine per mole of transition metal (rhodium). In some embodiments, the amount of monophosphine added to the reaction zone is from 40 to 350 moles of monophosphine per mole of transition metal (rhodium).

While the tetraphosphine ligand is likely to decompose to form one or more monophosphine compounds, the amount of monophosphine added to the reaction medium according to embodiments of this invention is much higher than would be expected from degradation. In other words, the vast majority of monophosphine in the reaction medium is added (eg, it is not formed from tetraphosphine present in the catalyst composition or in the reaction medium).

For commercial operation, ligand concentrations must be maintained by intermittent or continuous addition. To do this, the concentration of the ligand in the reaction mixture is regularly measured by one or more analytical methods; generally preferred is high performance liquid chromatography (HPLC). Unless otherwise indicated in this context, when mentioning the amount of monophosphine ligand in the reaction zone, the concentration of the ligand is determined using HPLC, as described in the "Examples" section. Ligand concentrations in such assays are often reported as weight percent; since it is often convenient to use it in such units in continuous operation. In some embodiments, the amount of monophosphine added to the reactor is greater than 1.5 percent by weight relative to the reaction medium in the reactor, based on the total weight of the reaction medium in the reactor. In some embodiments, the amount of monophosphine added to the reactor is from 1.5 to 13 percent by weight relative to the reaction medium in the reactor, based on the total weight of the reaction medium in the reactor.

In some embodiments, the addition of monophosphine to a hydroformylation reactor operated using tetraphosphine of formula (I) (as described herein) advantageously slows down the rate of hydroformylation that would be expected under normal conditions. That is, when said monophosphine is added, the decrease in the rate of hydroformylation over time is less than in a hydroformylation process carried out under the same conditions but without monophosphine. This can advantageously produce more aldehydes over a period of time using the same amount of transition metal/tetraphosphine catalyst.

In some embodiments, the addition of monophosphine to a hydroformylation reactor operated using a tetraphosphine of formula (I) (as described herein) advantageously provides a reduction in the consumption rate of the tetraphosphine ligand that would be expected under normal conditions. That is, when said monophosphine is added, the tetraphosphine used as a ligand decomposes at a slower rate than under the same conditions but without monophosphine. This can advantageously increase the life of the transition metal/tetraphosphine catalyst.

It is generally preferred to carry out the hydroformylation process in a continuous manner. Continuous hydroformylation processes are known in the art. The continuous process can be carried out in one pass, i. e. when a gaseous mixture containing unreacted olefinic starting material(s) and a gaseous aldehyde product is removed from the liquid reaction mixture, after which the aldehyde product is separated from it, and make-up olefinic starting material(s), carbon monoxide and hydrogen are fed into the liquid reaction medium for the next single pass without recycling the unreacted olefinic starting material(s). Such types of recycle are known in the art and may include a liquid recycle of a liquid medium containing an organophosphorus metal complex catalyst isolated from the desired aldehyde reaction product(s), as described, for example, in US 4,148,830, or a gas recycle, such as described , for example, in US 4247486, as well as, if necessary, a combination of liquid and gas recycle. The most preferred hydroformylation process comprises a continuous liquid catalyst recycle process. Suitable liquid catalyst recycling methods are described in, for example, US Pat. Nos. 4,668,651; 4774361; 5102505 and 5110990.

In one embodiment, aldehyde product mixtures may be separated from other components of the crude reaction mixtures in which aldehyde mixtures are formed by any suitable method such as, for example, solvent extraction, crystallization, distillation, evaporation, spread film evaporation, falling film evaporation, phase separation, filtering, or any combination thereof. It may be necessary to remove aldehyde products from the crude reaction mixture as they form with 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 Pat. Nos. 5,430,194 and 5,681,473.

As indicated above, the desired aldehydes can be isolated from reaction mixtures. For example, the recovery techniques described in US Pat. Nos. 4,148,830 and 4,247,486 can be used. of the reaction medium which is removed from the reaction zone may be sent to a recovery zone, e.g. an evaporator/separator, where the desired aldehyde product may be separated from the liquid reaction medium by distillation in one or more stages at normal, reduced or elevated pressure, condensed and collected in the product receiver and then cleaned if necessary. The remaining liquid reaction mixture containing the non-volatile catalyst can then be returned to the reactor, as can any other volatile materials, such as unreacted olefin, if necessary, along with the hydrogen and carbon monoxide dissolved in the liquid reaction mixture after they have been separated from the condensed aldehyde product, for example by distillation by any conventional method.

More specifically, the distillation and recovery of the desired aldehyde product from the reaction medium containing the organophosphorus metal complex catalyst can be carried out at any suitable and desired temperature. It is generally preferred that such a distillation be carried out at relatively low temperatures, for example below 150°C, and more preferably at a temperature in the range of 50°C to 140°C. In one embodiment, such an aldehyde distillation is carried out under reduced pressure, such as a total gas pressure that is substantially lower than the total gas pressure used in the hydroformylation, in the case of low-boiling aldehydes (e.g., C4-C6), or under vacuum, in the case of high boiling aldehydes (eg C7 or more). For example, it is common practice to treat the liquid reaction medium containing the hydroformylation reactor product under reduced pressure to vaporize a significant portion of the unreacted gases dissolved in the liquid medium, which now contains a much lower concentration of synthesis gas than its concentration in the reaction environment in the distillation zone, for example, in the evaporator/separator, where the desired aldehyde product is distilled. Generally, a distillation pressure ranging from vacuum pressure to a total gas pressure of 340 kPa is sufficient for most purposes.

In one embodiment, fluid gases may be used in the isolation zone to facilitate the distillation of the aldehyde. This boil-off gas is vaporized as described, for example, in US 8404903.

Elevated concentrations, high temperatures, and low partial pressures that occur in the recovery zone can adversely affect the catalyst, both in terms of catalyst deactivation and/or increased ligand consumption. As described below in the Examples section, an accelerated test method, referred to herein as the blocking method, was developed to demonstrate the effect of the release zone on the catalyst to evaluate various implementations.

Exemplary optically inactive aldehyde products of the hydroformylation processes of the embodiments of this invention depend on the olefin used as a 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, e.g. 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, gentriacontanal and 2-methyl-1-triacontanal, and the like.

In some embodiments in which propylene is an olefin undergoing 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, for example, the ratio of n-butyraldehyde to 2-methylpropionaldehyde (isobutyraldehyde) is usually described as the ratio N:I or simply N:I.

In one embodiment, the implementation of the catalyst contains rhodium, one or more equivalents of tetraphosphine and triphenylphosphine (for example, 1.5-12% wt.). For example, in a process using a catalyst composed of rhodium and tetraphosphine, the addition of triphenylphosphine may be chosen to reduce tetraphosphine catalyst consumption and deactivate the catalyst.

Some embodiments of the present invention are described in more detail further in the following section "Examples".

Examples

All parts and percentages in the following examples are by weight unless otherwise indicated. Ligand A concentration is expressed in equivalents of moles of ligand A per mole of rhodium. The pressures in the following examples are expressed in pounds per square inch of gauge pressure unless otherwise noted. All work, such as the preparation of catalyst solutions, was carried out under an inert atmosphere, unless otherwise indicated. Comparative experiments are not embodiments of this invention.

The gas composition (mole %) was measured using gas chromatography (GC) and partial pressures and then calculated from the total pressure according to Raoult's law.

The concentration of free tetradentate phosphine was measured by high performance liquid chromatography (HPLC). To prevent oxidation during analysis, phosphines were derivatized to stable phosphine sulfides by mixing with a diluent saturated with sulfur (50:50 v/v acetonitrile:THF saturated with elemental sulfur).

External standard HPLC analyzes were performed on an Agilent 1200 Infinity Series HPLC instrument equipped with a UHPLC SB-C8 3.0 mm, 1.8 µm guard column followed by a Zorbax SB-C8 analytical column (3.0 x 150 mm). The solvent gradient used was 55% water, the rest acetonitrile for 4 minutes; then brought to a ratio of 20: 80 water: acetonitrile in 22 minutes and finally returned to the original composition for the remaining 35 minutes of the chromatogram recording time. The solvent flow rate was 1.00 ml/min., the column temperature was maintained at 40°C. Two microliters of sample were injected into the system; the multiwavelength UV detector was set to 240 nm.

Obtaining ligand A

In the examples, a tetradentate phosphine compound, Ligand A, was used and was prepared as follows.

Synthesis of 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid. A 5 L reactor equipped with a jacket, an overhead stirrer, a bottom drain valve and a water-cooled condenser was charged with 1 L of methylene chloride and 50 g (0.247 mol) of pyrene. The mixture was stirred until the pyrene dissolved, after which 0.25 l of acetonitrile, 1.5 l of deionized water and 2.0 g of ruthenium (III) chloride were added. The resulting two-phase mixture was vigorously stirred and cooled to 18° C. by passing coolant through the jacket. Sodium periodate (total 500 g; 2.34 mol) was then added in small portions over 2.5 hours while maintaining the reactor temperature at 23-27°C. The reaction mixture, which was initially brown, quickly turned dark brown and finally brownish green. After stirring overnight (18 hours), mixing was stopped and the mixture was left to separate the layers. The bottom layer was poured into a Buchner funnel, collecting the crude greenish brown solid, which was washed with methylene chloride (2 x 500 ml) and dried on the filter under a stream of air. The solid was then returned to the reactor and boiled with 1.5 L of acetone for 1 hour. After cooling to room temperature, pour the yellow solution into a Buchner funnel and concentrate the filtrate on a rotary evaporator to give a yellow solid. The crude product, tetraacid, was 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 was dried and purged with nitrogen overnight. The 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 atmosphere. The resulting solution was stirred and cooled to 0°C by passing the cooled liquid through the reactor jacket. A solution of lithium aluminum hydride in THF (1 M; 666 mL, 0.665 mol) was then added via a peristaltic pump over 2 hours. During this time, the mixture was vigorously stirred and the temperature of the reactor was maintained at 0-2°C; to ensure safety, a weak stream of nitrogen was fed into the reactor, and the effluent stream was passed through a condenser to clean the reactor from evolving hydrogen. After completion of the addition of lithium aluminum hydride, the contents of the reactor were stirred in the cold state for another 15 minutes, then left to slowly warm to room temperature. After stirring at room temperature for 30 minutes, the contents of the reactor were heated to 65° C. and stirred overnight under a gentle stream of nitrogen. The next morning the reactor was cooled to 0° C. and quenched by slowly adding 25 ml of water via a peristaltic pump, then 50 ml of 10% NaOH and 75 ml of water at 0-7° C. over 1.5 hours. Hydrogen was evolved during the quenching process, and therefore a purge was carried out using nitrogen. The quenched solution was allowed to slowly warm to room temperature and then poured from the reactor into a Buchner funnel. The collected solid was 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 solid was 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 a light yellow product was obtained (yield 77.1%, purity about 97%). 1H 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. 13C 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 L reactor was dried and purged with nitrogen overnight, and then 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 was stirred and cooled to 0°C. Thionyl chloride (1.071 g, 9.01 mol) was then slowly added via a peristaltic pump over 2 hours while maintaining the reactor temperature at about 0°C; during the addition, the reactor was purged with nitrogen to remove HCl and SO2 formed, while the off-gases were passed through a water scrubber. The reaction solution was then allowed to warm to room temperature and stirred for 30 minutes, after which it was heated to reflux (about 45° C.) overnight. The next day, the solution was cooled to 15°C and unloaded from the reactor. The methylene chloride was removed by atmospheric distillation and the residual thionyl chloride was removed by vacuum distillation. The resulting residue was dried first on a rotary evaporator, then dried in a vacuum oven at 60° C. overnight to give 58.1 g of a yellow solid. (yield 100%, purity about 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) ppm 13C NMR (400 MHz, CDCl2) δ 136.9, 135.5, 131.3, 130.3, 45.0 ppm

Synthesis of (biphenyl-2,2',6,6'-tetramethandiyl)tetrakis(diphenylphosphine) (ligand A). Lithium wire (2.1 g, 300 mmol) was cut into small pieces and loaded into a 250 ml dry box flask along with anhydrous THF (130 ml). The suspended solution was transferred to a Schlenk line and cooled in an ice water bath under nitrogen. Chlorodiphenylphosphine (28.1 ml, 151.7 mmol) was added dropwise at 0°C over 50 minutes and then stirred for another 30 minutes at 0°C. During this time, the color changed from cloudy 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(chlorimethyl)-1,1'-biphenyl (12.7 g, 37 mmol) in THF (60 mL) was added dropwise over 50 minutes and then stirred cold for further 20 minutes. The solution was then allowed to slowly warm to room temperature and then transferred to a dry box and stirred overnight. Then added degassed methylene chloride (300 ml) and water (150 ml) and left the resulting mixture for separation. The bottom layer was transferred to a round bottom flask and concentrated on a rotary evaporator at 30° C. to give a solution of the crude product in THF. While heating the resulting solution at 65° C. under a stream of nitrogen, degassed ethanol (100 ml) was slowly added. During the addition of ethanol, a precipitate of a white solid began to form. The mixture was then allowed to cool and placed in a refrigerator overnight; the resulting solid was collected the next day by dry box filtration and washed with ethanol (2 x 50 ml). Drying under vacuum overnight gave the desired product as a white powder (yield 90%, purity 99%). 31P 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, tetraphosphine, has the following structure:

Reference ligand B

Reference ligand B is BISBI (neither monophosphine nor tetradentate phosphine), which is known to form an active and selective hydroformylation catalyst. Methods for preparing BISBI and examples of its use as a hydroformylation ligand are provided, for example, in US Patent No. 4,694,109. which it was on delivery. The structure of BISBI (Ligand B) is shown in FIG. 2.

Fig. 2. Comparative ligand B; BISBI.

General way

Unless otherwise indicated, the examples and comparative experiments were carried out in 90 ml Fischer-Porter flow reactors equipped with precise temperature and gas flow controls. Exhaust gases from the reactors were analyzed using an on-board GC to determine partial pressures. Mixing in the flow reactor was carried out using a continuous flow of gas from the bubbler at the bottom of the reactor. This reactor design is detailed in US Pat. No. 5,731,472, the contents of which are incorporated herein by reference.

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

In these examples, an accelerated test method, referred to in this context as a blocking method, was used to demonstrate the effect of the isolation zone on the catalyst. This test method involves treating the solubilized activated rhodium complex catalysts under conditions of low partial pressures and high temperatures for a much longer period of time than in a conventional continuous liquid medium recycle hydroformylation process to obtain practically meaningful results. For example, the catalyst deactivation and/or ligand consumption described herein, which can occur in continuous recycle hydroformylation, can take several weeks to be quantified by conventional aldehyde distillation recovery methods as the catalyst is subjected to evaporator conditions in for only a few minutes a day, while an accelerated test (blocking method) can be carried out for several hours or days by continuously keeping the liquid reaction product at high temperatures for the distillation of aldehydes for an extended period of time. Lockout periods include periods of time during which the reactor is hermetically sealed at reduced pressure and high temperature. This method is designed to simulate the effect of the isolation zone on the catalyst solution.

Comparative Experiment A

The reactor was loaded with tetraglyme (20 ml), rhodium (200 ppm) and ligand A (1.5 eq.). Hydroformylation was carried out at 20 psi CO, 50 psi H2 and 20 psi propylene at 90° C. and the initial hydroformylation rate and N:I ratio were measured. After operating overnight, an HPLC sample was taken from the reactor to determine the concentration of free ligand A, the reactor was depressurized to a total pressure of 10 psi and blocked at 115° C. overnight. After a blocking period, hydroformylation was started again under the original conditions, and a sample of the HPLC catalyst solution was taken; then the blocking procedure was repeated a second time.

Comparative Experiment B

The method of Comparative Experiment A was repeated except for the amount of ligand A added (5 eq.).

Examples 1-4

The method of Comparative Experiment A and B was repeated except for the addition of TPP (5 or 10% by weight).

The results obtained in comparative experiment A and B, as well as in examples 8-11, are presented in tables 1 and 2.

Table 1

TPP Ligand A Initial value after 1st block after 2nd block % wt. equiv. speed N:I speed N:I speed N:I Wed pr. A 0 1.5 0.1254 42.7 0.0164 23.0 0.0119 18.0 Wed pr. 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

Ligand A, % wt. by HPLC original value after 1st block after 2nd block Wed pr. A 0.0644 0.0087 below detection limit Wed pr. 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 the N:I value observed for catalyst solutions consisting of only rhodium and ligand A (comparative experiments A and B) decreased significantly after blocking, as did the concentration of free ligand A, indicating degradation of the ligand. Although the initial rates of hydroformylation in Examples 1-4 are lower, the catalyst solutions of this invention demonstrate the ability to withstand blocking conditions, both in terms of reducing the degree of catalyst deactivation and in terms of reducing the rate of consumption of the ligand. Because chelating ligands are typically expensive, reducing the consumption of tetradentate phosphine improves the profitability of the process.

Comparative experiments C-D

The method of comparative experiments A and B was repeated except for the use of comparative ligand B.

Comparative experiments E-H

The method of Examples 1-4 was repeated except for the use of comparative ligand B.

The results for the comparative C-H experiments are summarized in Table 3.

Table 3

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

It has been observed that catalysts consisting only of rhodium and comparative ligand B are adversely affected by the blocking period, both in terms of catalyst deactivation and in terms of N:I. While catalysts composed of rhodium, TPP, and comparative ligand B also show improved stability, they do not achieve an N:I greater than 11. Without being limited by theory, this low N:I suggests that the rhodium-BISBI catalyst is more readily inhibited by TPP and hence the resulting mixture of active complexes contains a relatively low amount of active and selective rhodium-BISBI complex.

Examples 5-10

Tetraglyme (20 ml), rhodium (200 ppm), Ligand A (1.5 or 3 eq) and TPP (3-5 wt %) were charged to each of the six reactors. Hydroformylation was carried out at 20 psi CO, 50 psi H2 and 20 psi propylene at 90° C. and the initial hydroformylation rate and N:I ratio were measured. The reactors were blocked twice at 10 psi and 115° C. overnight; after each blocking period, the characteristics of the catalyst were determined under the initial conditions used before blocking. An additional amount of Ligand A (one equivalent) was then added to each reactor and the change in characteristics achieved was measured. A summary of the results is presented in Table 4.

Table 4

TPP Ligand A Initial value after 1st block after 2nd block After adding more ligand A % wt. equiv. 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 is noted that the initial rate of hydroformylation is inversely proportional to the concentration of TPP, and that the N:I value is directly proportional to the concentration of ligand A; in addition, the possibility of increasing N:I by adding an additional amount of ligand A shortly before the end of the experiment was demonstrated. Without being limited by theory, this suggests that the observed catalysis is the result of a mixture of active complexes of the mixture, and in addition that some rhodium exists in a relatively inactive form, probably in the form of a complex of rhodium with an organotriphosphorus compound, consisting of ligand A and TPP . The addition of additional Ligand A returns the N:I value to its original value (before blocking periods), indicating that the system can recover from the initial degradation of Ligand A.

Comparative Experiment I

The reactor was loaded with tetraglyme (20 ml), rhodium (350 ppm) and ligand A (4 eq.) at 90°C. The reactor was rapidly purged with 1:1 synthesis gas and then an HPLC sample was taken to determine the concentration of free ligand A. Air (250 ml) was then passed through the solution with a syringe and the HPLC catalyst solution was sampled again to determine the change in the concentration of ligand A.

Example 11

The method of Comparative Experiment I was repeated except for the addition of TPP (12% by weight).

The results of Comparative Experiment I and Example 11 are summarized in Table 5.

Table 5

TPP (wt %) Ligand A (% wt.) - initial value Ligand A (% wt.) - after adding air Loss of ligand A (%) - after adding air Wed pr. I 0 0.7492 0.5439 27 Etc. eleven 12 0.8181 0.8030 1.8

The results presented in Table 5 demonstrate that the presence of TPP helps to protect tetraphosphine from degradation due to oxidation, which can occur under operating conditions from small leaks in the system or accidental air entry during equipment maintenance, etc.

Claims (23)

1. A method for slowing down the deactivation of a catalyst in a hydroformylation process, comprising: (a) contacting an olefin with carbon monoxide, hydrogen and a catalyst containing (A) a transition metal in which the transition metal contains rhodium, (B) a tetraphosphine having the following structure:

where each P represents a phosphorus atom, and each of R1-R46 independently represents hydrogen, C1-C8 alkyl group, aryl group, alkaryl group or halogen, and said contacting is carried out in one or more reaction zones and under hydroformylation conditions; And (b) adding to the reaction zone a monophosphine having the following structure:

where P represents a phosphorus atom, and each of Y1-Y3 independently represents an aryl group, an alkaryl group, a cycloalkyl group, a benzyl group, a C3-C8 alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen. 2. A method for slowing down the consumption of tetraphosphine ligand in the hydroformylation process, including: (a) contacting an olefin with carbon monoxide, hydrogen and a catalyst containing (A) a transition metal in which the transition metal contains rhodium, (B) a tetraphosphine having the following structure:

where each P is a phosphorus atom and each of R1-R46 is independently hydrogen, a C1-C8 alkyl group, an aryl group, an alkaryl group or a halogen, and said contacting is carried out in one or more reaction zones and under hydroformylation conditions; And (b) adding to the reaction zone a monophosphine having the following structure:

where P represents a phosphorus atom, and each of Y1-Y3 independently represents an aryl group, an alkaryl group, a cycloalkyl group, a benzyl group, a C3-C8 alkyl group, an alkoxy group of 1-8 carbon atoms, an aryloxy group, or a halogen. 3. The method according to claim 1 or 2, characterized in that the monophosphine is triphenylphosphine. 4. The method according to claim 1 or 2, characterized in that the monophosphine is a bulk monophosphine. 5. The method according to any one of the preceding claims, characterized in that each of R1-R46 is hydrogen. 6. Process according to any one of the preceding claims, characterized in that the olefin is propylene. 7. The method according to claim 1 or 2, characterized in that the decrease in the rate of hydroformylation over time is less than in the method carried out under the same conditions, but without monophosphine. 8. The method according to claim 2, characterized in that the consumption rate of the tetraphosphine ligand in the hydroformylation process is lower than in the hydroformylation process carried out under the same conditions, but without monophosphine. 9. A process according to any one of the preceding claims, characterized in that the amount of added monophosphine is at least 40 moles of phosphine per mole of transition metal. 10. A process according to any of the preceding claims, wherein the amount of monophosphine added to the reaction zone is more than 1.5 percent by weight relative to the reaction medium in the reaction zone, based on the total weight of the reaction medium in the reaction zone. 11. The method according to p. 1, characterized in that additional monophosphine having the specified structure is added to the components (A) and (B) in stage (a).