GB2127708A - Carbonylation catalysts for the preparation of carboxylic acids, anhydrides and esters - Google Patents

Abstract

A carboxylic acid, a carboxylic acid anhydride or a carboxylic acid ester such as propionic acid, propionic anhydride or methyl propionate is prepared by carbonylation of an olefin, such as ethylene, in the presence of water, a carboxylic acid and/or an alcohol and in the presence of a halide, wherein there is used a catalyst comprising a molybdenum- nickel-alkali metal, a tungsten-nickel alkali metal, or a chromium-nickel- alkali metal co-catalyst component. Also, a catalyst for the process.

Description

SPECIFICATION Preparation of carboxylic acids, anhydrides and esters This invention relates to the carbonylation of olefins to produce carboxylic acids, more particularly mono-carboxylic acids, and especially lower alkanoic acids, such as propionic acid, the an hydrides of such acids and the esters of these acids, especially the lower alkanoic esters.

Carboxylic acids have been known as industrial chemicals for many years and large amounts are used in the manufacture of various products.

Producing carboxylic acids by the action of carbon monoxide upon olefins (carbonylation) has been described, for example, in Reppe et al U.S. Pat.

2,768,968. However, such prior proposals involving olefin carbonylation reactions have required the use of very high pressures. Olefin carbonylation processes effective at lower pressures have also been proposed. Craddock et al U.S. Pats. 3,579,551; 3,579,522 and 3,816,488, for example, describe the carbonylation of olefins in the presence of compounds and complexes of Group VIII noble metals such as iridium and rhodium in the presence of iodide under more moderate pressures than those contemplated by Reppe et al. These lower-pressure carbonylation disclosures, however, require the use of the expensive noble metals. More recently, Belgian Pat. 860,557 has proposed the preparation of carboxylic acids by carbonylation of alcohols in the presence of a nickel catalyst promoted by a trivalent phosphorus compound and in the presence of an iodide.

The production of anhydrides by the action of carbon monoxide upon olefins has also been described, for example, in the above-mentioned Reppe et al U.S. Pat. 2,768,968, using very high pressures. Foster et al U.S. Pat. 3,852,346 describes the carbonylation of olefins in the presence of compounds of Group VIII noble metals such as iridium and rhodium and in the presence of an iodide under more moderate pressures than those contemplated by Reppe et al. However, this process like the processes of the Craddock et al patents, requires the use of expensive, relatively rare metals.

The production of carboxylic acid esters by the action of carbon monoxide upon olefins has been described in various patents by processes involving several types of catalysts. For example, Slaugh U.S. Patent 3,168,553 shows the reaction of carbon monoxide with an olefinic hydrocarbon in the presence of alcohols by using a Group Vlllb transition metal carbonyl catalyst which contains cobalt, ruthenium, rhodium or iridium in complex combination with carbon monoxide and a trialkyl phosphorus. Anderson et al. U.S. Patent 3,040,090 reacts carbon monoxide, an ethylenically-unsaturated compound and an alcohol in the presence of a Group VIII noble metal chelate. Morris et al. U.S.Patent 3,917,677 also shows a process involving a reaction among carbon monoxide, ethylenically-u nsaturated compounds and alcohols which is characterized by using a catalyst containing a rhodium component and a tertiary organo-phosphorus component. This patent contains a discussion of the prior art and the limitations of the prior art procedures, particularly, the poor yields obtainable with them. Furthermore, the prior art process in general, require relatively high pressures. Even though improved yields are apparently obtained by the process of U.S. Patent 3,917,677, that process requires the use of a rhodium catalyst.

U.S. Patents 4,335,058, 4,354,036 and 4,372,889, disclose related processes for the carbonylation of olefins which use a molybdenum-nickel or a tungsten-nickel cocatalyst in the presence of a promoter comprising an organo-phosphorus or an organo-nitrogen compound such as a phosphine of a tertiary amine, to produce carboxylic and anhydrides, carboxylic acid esters and carboxylic acids, respectively. While these processes involve nickel catalysts which make possible carbonylation of olefins at modest pressures without requiring the use of a nobel metal catalyst, and while these processes are highly effective for their intended purpose, there is room for improvement in terms of reaction rate and productivity without need to use organic promoter.

The present invention provides improved processes for the manufacture of carboxylic acids, especially lower alkanoic acids, such as propionic acid, the anhydrides of such acids, and their esters, which require neither high pressures nor Group VIII noble metals and make possible the production of carboxylic acids, anhydrides and esters in high yields in short reaction times without need for organic promoters.

In accordance with the invention, carbonylation of an olefin is carried out by using a molybdenum-nickel-alkali metal, a tungstennickel-alkali metal or a chromium-nickel-alkali metal co-catalyst in the presence of a halide, preferably an iodide, a bromide and/or a chloride, especially an iodide, and in the presence of a coreactant which may be water, a carboxylic acid or an alcohol. Thus, when it is desired to produce a carboxylic acid, the carbonylation is carried out in the presence of water. When it is desired to produce a carboxylic acid anhydride, the carbonylation is carried out under substantially anhydrous conditions in the presence of a carboxylic acid and, to produce an ester, the carbonylation is effected in the presence of an alcohol.The surprising discovery has been made that this co-catalyst system in an environment of the character indicated makes possible the carbonylation of olefins not only at relatively low pressures but with rapid, high-yield production of carboxylic acids, anhydrides and esters.

The outstanding effectiveness of the catalysts system of the processes of this invention is particularly surprising in view of the experimental data reported in European published application 0 035 458 which shows the carbonylation of methanol to produce acetic acid and in which experiments using nickel in combination with molybdenum or tungsten or chromium showed absolutely no reaction even after two hours. It has also been observed that when nickel-based catalysts are ordinarily used in carbonylation reactions, there is a tendency for the nickel components to be volatilized and to appear in the vapors from the reaction.It has been surprisingly found that with the catalyst system of this invention, the volatility of the nickel is strongly suppressed and a highly-stable catalyst combination results, especially in the case of the molybdenum-containing co-catalyst, which is the preferred co-catalyst.

Thus, in accordance with the invention, carbon monoxide is reacted with an olefin, such as a lower alkene, in the presence of a halide, e.g., a hydrocarbyl halide, especially a lower alkyl halide, e.g., such as ethyl iodide, in the presence of the co-catalyst which has been identified above, and in the presence of water, a carboxylic acid (under an hydros conditions) or an alcohol. Propionic acid, propionic an hydride or a propionic acid ester, for example, can be effectively prepared in a representative case by subjecting ethylene to carbonylation in the presence of the appropriate co-reactant and in the presence of the catalyst system of this invention. Propionic acid is employed as the co-reactant in the case of propionic anhydride.

In like manner, other alkanoic acids, such as butyric acid and valeric acid, their anhydrides and esters can be produced by carbonylating the corresponding alkene such as propylene, butene1, butene-2, the hexenes, the octenes, and the like. Similarly, other alkanoic acids, for example, capric acid, caprylic acid, and lauric acid, and like higher carboxylic acids, their anhydrides and esters, are produced by carbonylating the corresponding olefin.

The reactant olefin may be any ethylenically unsaturated hydrocarbon having from 2 to about 25 carbon atoms, preferably from 2 to about 1 5 carbon atoms. The ethylenically unsaturated compound has the following general structure: R2RqC=CR3R4 wherein R1, R2, R3 and R4 are hydrogen or the same or different alkyl, cycloalkyl, aryl, alkaryl, aralkyl or wherein one of said R, and R2 and one of said R3 and R4 together form a single alkylene group having from 2 to about 8 carbon atoms. R1, R2, R3 and R4 can be branched and can be substituted with substituents which are inert in the reactions of the invention.

Examples of useful ethylenically unsaturated hydrocarbons are ethylene, propylene, butene-1, butene-2, 2 methylbutene-1, cyclobutene, hexene- 1, hexene-2, cyclohexene, 3-ethylhexene- 1, isobutylene, octene-1, 2-methylhexene-1, ethylcyclohexene, decene-1, cycloheptene, cyclooctene, cyclononene, 3,3-dimethylnonene-l , dodecene-1, undecene-3, 6-propyldecene-1, tetradecene-2, 3-amyldecene- 1 etc., hexadecene 1, 4-ethyltridecene-1, octadecene-1, 5,5- dipropyldodecene-1, vinylcyclohexane, allylcyclohexane, styrene, p-methylstyrene, alphamethylstyrene, p-vinylcu mene, beta-vinyl naphthalene, 1 ,1 -diphenylbutene- 1, 3-benzyl- heptene-1, divinylbenzene, 1 -allyl-3-vinylbenzene, etc.Of the olefins referred to above, the alpha hydrocarbon olefins and olefins having 2 to about 10 carbon atoms are preferred, e.g. ethylene, propylene, butene-1, hexene-1, heptene-1, octene-1,and the like, i.e., wherein R1, R2, R3 and R4 are hydrogen or alkyl groups totalling 1 to 8 carbon atoms, preferably the lower alkenes, i.e., alkenes of 2 to 6 carbon atoms, especially ethylene.

The co-reactant carboxylic acid, in the case of anhydride production, may be in general any carboxylic acid having 1 to about 25 carbons and having the formula: RCOOH wherein R is hydrogen, alkyl, cycloalkyl or aryl.

Preferably R has 1 to about 18 carbon atoms and most preferably R is alkyl having 1 to about 12 carbon atoms, especially 1 to 6 carbon atoms e.g., methyl, ethyl, propyl, isobutyl, hexyl, nonyl, and the like, or is aryl with 6 to about 9 carbon atoms, e.g., phenyl, tolyl, and the like.

Examples of useful acids are acetic, propionic, n-butyric, isobutyric, pivalic, n-valeric, n-caproic, stearic, benzoic, phthalic, terephthalic, toluic, 3- phenylhexanoic acid, 2-xylylpalmitic acid and 4phenyl-5-isobutyl stearic acid. The preferred acids are the fatty or alkanoic acids having 2 to about 1 2 carbon atoms, e.g., acetic, propionic, n-butyric, sobutyric, pivalic, caproic, undecylic, and the like.

Especially preferred are the lower alkanoic acids.

i.e. wherein R is an alkyl group of 1 to 6 carbon atoms, especially propionic acid. R can be branched and can be substituted with substituents which are inert in the reactions of the invention.

It is preferred that the reactants be selected so that the resulting anhydride will be a symmetrical anhydride, i.e., having two identicai acyl groups.

The co-reactant alcohol may be in general any alcohol having the formula ROH, where R is alkyl, cyclo-alkyl, aryl, alkaryl or aralkyl or mixtures thereof. Preferably R has 1 to about 1 8 carbons and most preferably R is alkyl having 1 to about 1 2 carbons, e.g., methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, nonyl, and the like, or is aralkyl with 7 to about 14 carbons, e.g., benzyl, phenethyl, and the like.

Examples of suitable alcohols include methanol, ethanol, propanol, isopropanol, butanol, tertiary butanol, pentanol, hexanol, 2ethylhexanol, octanol, decanol, 6-pentadecanol, cyclopentanol, methylcyclopentanol, cyclohexanol, benzyl alcohol, alpha alpha-dimethyl benzyl alcohol, alpha alpha-dimethyl benzyl alcohol, alpha-ethylphenethyl alcohol, naphtyl carbinol, xylyl carbinol, tolyl carbinol, and the like.

In most preferred embodiments of the invention, carbon monoxide is reacted with ethylene and water, propionic acid or methanol in the presence of the co-catalyst halide system of the character described above to produce priopionic acid, propionic anhydride or methyl propionate, in reactions which may be expressed as follows: C2H4+CO+H20eC2H5COOH QH4+CO+C2H5COOHC2H5COOCOC2H5 C2H4+CO+CH30HeC2H5COOCH3 Carbon monoxide is removed in the vapor phase along with unreacted olefin when the olefin is normally gaseous, e.g., ethylene, and, if desired, recycled.Normally-liquid and relatively-volatile components such as alkyl halide, normally-liquid unreacted olefin and the co-reactant (water, carboxylic acid or alcohol) and any by-products present in the final product mixture can be readily removed and separated from each other, as by distillation, for recycling, and the net yield of product is substantially exclusively the desired carboxylic acid, anhydride or ester. In the case of liquid-phase reaction, which is preferred, the organic compounds are easily separated from the metal-containing components, as by distillation.

The reaction is suitably carried out in a reaction zone to which the carbon monoxide, the olefin, the co-reactant, the halide, and the co-catalyst are fed. When an anhydride is the desired product, no water is produced and as mentioned, the reaction is carried out under substantially anhydrous conditions. In the case of ester production, the liquid-phase reaction is preferably carried out under boiling conditions wherein all volatile components are removed in the vapor phase, leaving the catalyst in the reactor.

As will be apparent from the foregoing equations, a carbonylation reaction of the character described selective to carboxylic acid, carboxylic acid an hydride or carboxylic acid ester requires at least one mol of carbon monoxide and one mol or the co-reactant (water, carboxylic acid or alcohol) per mol (equivalent) of ethylenically unsatured linkage reacted. Thus, the olefin feedstock is normally charged with equimolar amounts of the co-reactant, although more of the co-reactant may be used.

In carrying out the processes of the invention, a wide range of temperatures, e.g., 250 to 3500C are suitable but temperatures of 1000 to 2500C are preferably employed, and the more preferred temperatures generally lie in the range of 1250 to 2250C. Temperatures lower than those mentioned can be used, but they tend to lead to reduce reaction rates, and higher temperatures may also be employed but there is no particular advantage in their use. The time of reaction is also not a parameter of the process and depends largely upon the temperature employed, but typical residence times, by way of example, will generally fall in the range of 0.1 to 20 hours. The reaction is carried out under super atmospheric pressure but as previously mentioned, it is a feature of the invention that excessively high pressures, which require special high-pressure equipment, are not necessary.In general, the reaction is effectively carried out by employing a carbon monoxide partial pressure which is preferably at least 1 5 but less than 2,000 psi, most preferably 1 5 to 1,000 psi, and particularly 30 to 200 psi, although CO partial pressures of 1 to 5,000 or even up to 10,000 psi can also be employed. By establishing the partial pressure of carbon monoxide at the values specified, adequate amounts of this reactant are always present. The total pressure is, of course, that which will provide the desired carbon monoxide partial pressure, and preferably it is that required to maintain the liquid phase and, in this case, the reaction can be advantageously carried out in an autoclave or similar apparatus. At the end of the desired residence time, the reaction mixture is separated into its several constitutents, as by distillation.Preferably, the reaction product is introduced into a distillation zone which may be a fractional distillation column, or a series of columns, effective to separate the volatile components from the product anhydride or ester and to separate the product from the less volatile catalyst components of the reaction mixture. The boiling points of the volatile components are sufficiently far apart that their separation by conventional distillation presents no particular problem. Likewise, the higher-boiling organic components can be readily distilled away from the metal catalyst components. The thusrecovered co-catalyst, including the halide component, can then be combined with fresh amounts of olefin, carbon monoxide and coreactant and reacted to produce additional quantities of carboxylic acid, anhydride or ester.

When the reaction is run under boiling conditions the effluent is entirely in the vapor phase and, after condensation, the components can be separated from each other as described above.

Although not necessary, the process can be carried out in the presence of a solvent or diluent.

The presence of a higher-boiling solvent of diluent, preferably the product itself, e.g., propionic acid, propionic anhydride or a propionic acid ester, in the case of ethylene carbonylation, will make it possible to employ more moderate total pressures. Alternatively, the solvent or diluent may be any organic solvent which is inert in the environment of the process, such as hydrocarbons, e.g., octane, benzene, toluene, xylene and tetralin, or carboxylic acids. A carboxylic acid, if used, should preferably correspond to the carboxylic acid moiety in the product being produced since it is preferred that the solvent employed be indigenous to the system, e.g., propionic acid in the case of ethylene carbonylation, although other carboxylic acids, such as acetic acid, can also be used.A solvent or diluent, when not the product itself, is suitably selected which has a boiling point sufficiently different from the desired product in the reaction mixture so that it can be readily separated, as will be apparent to persons skilled in the art. Mixtures can be used.

The carbon monoxide is preferably employed in substantially pure form, as available commercially, but inert diluents such as carbon dioxide, nitrogen, methane, and noble gases can be present, if desired. The presence of inert diluents does not affect the carbonylation reaction, but their presence makes it necessary to increase the total pressure in order to maintain the desired CO partial pressure. Hydrogen which may be present as an impurity is not objectionable and even may tend to stabilize the catalyst. Indeed, in order to obtain low CO partial pressures, the CO fed may be diluted with hydrogen or any inert gas such as these mentioned above. Amounts of diluent gas up to 95% can be used.

The co-catalyst components can be employed in any convenient form, viz., in the zero valent state or in any higher valent form. For example, the nickel and the molybdenum, tungsten or chromium can be the metals themselves in finely divided form, or a compound, both organic or inorganic, which is effective to introduce the cocatalyst components into the reaction system.

Thus, typical compounds include the carbonate, oxide, hydroxide, bromide, iodide, chloride, oxyhalide, hydride, lower alkoxide (methoxide), phenoxide, or Mo, W, Cr or Ni carboxylates wherein the carboxylate ion is derived from an alkanoic acid of 1 to 20 carbon atoms, such as acetates, butyrates, decanoates, laurates, benzoates, and the like. Similarly, complexes of any of the co-catalyst components can be employed, e.g., carbonyls and metal alkyls as well as chelates, association compounds and enol salts. Examples of other complexes include bis (triphenylphosphine) nickel dicarbonyl, tricyclopentadienyl trinickel dicarbonyl, tetral(is (triphenylphosphite) nickel, and corresponding complexes of the other components, such as molybdenum hexacarbonyl and tungsten hexacarbonyl.

Particularly preferred are the elemental forms, compounds which are halides, especially iodides, and organic salts, e.g., salts of the monocarboxylic acid corresponding to the carboxylic acid moiety in the product being produced.

The alkali metal component, e.g., a metal of Group 1A of the Periodic Table such as lithium, potassium, sodium, and cesium, is suitably employed as a compound, especially a salt, and most preferably a halide, e.g., an iodide. The preferred alkali metal is lithium. The alkali metal component can, however, also be employed as the hydroxide, carboxylate, alkoxide or in the form of other convenient compounds such as are referred to above in connection with the other cocatalyst components, and typical alkali metal components are illustrated by sodium iodide, potassium iodide, cesium iodide, lithium iodide, lithium bromide, lithium chloride, lithium acetate, and lithium hydroxide.

It will be understood that the above-mentioned compounds and complexes are merely illustrative of suitable forms of the several co-catalyst components and are not intended to be limiting.

The specified co-catalyst components employed may contain impurities normally associated with the commercially available metal or metal compounds and need not be purified further.

The amount of each co-catalyst component employed is in no way critical and is not a parameter of the process of the invention and can vary over a wide range. As is well known to persons skill in the art, the amount of catalyst used is that which will provide the desired suitable and reasonable reaction rate since reaction rate is influenced by the amount of catalyst. However, essentially any amount of catalyst will facilitate the basic reaction and can be considered a catalytically-effective quantity.

Typically, however, each catalyst component is employed in the amount of 1 millimol to 1 mol per liter of reaction mixture, preferably 1 5 millimoles to 500 millimoles per liter and most preferably 1 5 millimoles to 150 millimoles per liter.

The ratio of nickel to the molybdenum, tungsten, or chromium co-catalyst component can vary. Typically, it is one mol of the nickel component per 0.01 to 100 mols of the second co-catalyst component, i.e., the molybdenum, tungsten, or chromium component. Preferably the nickel component is used in the amount of 1 mol per 0.1 to 20 mols, most preferably 1 mol per 1 to 10 mols of the second co-catalyst component.

Similarly, the ratio of nickel to the alkali metal component can vary, e.g., one mole of nickel per 1 to 1000 mols of alkali metal component, preferably one mole per 10 to 100 moles and most preferably one mole per 20 to 50 moles.

The amount of halide component may also vary widely but, in general, it should be present in an amount of at least 0.1 mol (expressed as elemental halogen) per mol of nickel. Typically, there are used 1 to 100 mols of the halide per mol of nickel, preferably 2 to 50 mois per mol.

Ordinarily, more than 200 mols of halide per mol of nickel are not used. It will be understood, however, that the halide component does not have to be added to the system as a hydrocarbyl halide but may be supplied as another organic halide or as the hydrohalide or other inorganic halide, e.g., a salt, such as the alkai metal or other metal salt, or even as elemental halogen, e.g., iodine or bromine.

As previously mentioned, the catalyst system of this invention comprises a halide, especially an iodide, component and a molybdenum-nickelalkali metal, tungsten-nickel-alkali metal, or chromium-nickel-alkali metal co-catalyst component. The catalyst system of this invention permits the production of carboxylic acids, carboxylic acid anhydrides and carboxylic acid esters in high yields in short reaction times without the use of Group VIII noble metals, and the presence of the alkali metal component together with the molybdenum, tungsten or chromium component makes possible good results with relatively small amounts of co-catalyst components and reduced quantities of nickel in comparison with prior art processes involving a nickel-containing catalyst.

A particular embodiment of the catalyst comprising the molybdenum-nickel-alkali metal, tungsten-nickel-alkali metal, or chromium-nickelalkali metal co-catalyst component and the halide component can be represented by the following formula: X:T:Z:Q, where X is molybdenum, tungsten or chromium, T is nickel, X and T being in zero valent form or in the form of a halide, an oxide, a carboxylate of 1 to 20 carbon atoms, a carbonyl or a hydride; Z is a halide source which is hydrogen halide, halogen, an alkyl halide wherein the alkyl group contains 1 to 20 carbon atoms or an alkali metal halide, and Q is the alkali metal component.The preferred alkali metal is lithium as previously indicated, and is in the form of an iodide, a bromide, a chloride or a carboxylate as defined for X and T, the molar ratio of X to T being 0.1-10:1, the molar ratio of X+T to Q being 0.1-10:1, and the molar ratio of Z to X+T being 0.01-0.1:1.

It will be apparent that the above-described reaction lends itself readily to continuous operation in which the reactants and catalyst are continuously supplied to the appropriate reaction zone and the reaction mixture continuously distilled to separate the volatile organic constituents and to provide a net product consisting essentially of carboxylic acid, an hydride or ester with the other organic components being recycled and, in a liquid-phase reaction, a residual catalyst containing fraction also being recycled.

It is also be apparent that the catalytic reaction involved in the process of the invention can be carried out in the vapor phase, if desired, by appropriate control of the total pressure in relation to the temperature so that the reactants are in vapor form when in contact with the catalyst. In the case of vapor-phase operation, and in the case of liquid-phase operation, if desired, catalyst components may be supported i.e., they may be dispersed on a carrier of conventional type such as alumina, silica, silicon carbide, zirconia, carbon, bauxite, attapulgus clay, and the like. The catalyst components can be applied to the carriers in conventional manner, e.g., by impregnation of the carrier with a solution of the catalyst component.Concentrations upon the carrier may vary widely, e.g., 0.01 weight percent to 10 weight percent, or higher. Typical operating conditions for vapor-phase operation are temperatures of 100" to 3500C, preferably 1500 to 2750C and most preferably 1750 to 2550C, a pressure of 1 to 5,000 p.s.i.a., preferably 59 to 1,500 p.s.i.a. and most preferably 1 50 to 500 p.s.i.a., with space velocities of 50 to 10,000 hr.-l, preferably 200 to 6,000 her.~' and most preferably 500 to 4,000 hr.-l (STP). In the case of a supported catalyst, the iodide component is included with the reactants and not on the support.

The following examples will serve to provide a fuller understanding of the invention, but it is to be understood that they are given for illustrative purposes only, and are not to be construed as limitative of the invention. In the examples, all parts are by weight, unless otherwise indicated.

Example 1 In this example, a magnetically-stirred pressure vessel with a glass liner was employed. The reaction vessel was charged with 1 2 parts water, 11.9 parts ethyl iodide, 0.76 parts nickel iodide (Nil2), 1.4 parts molybdenum hexacarbonyl, 1 4.3 lithium iodide and 60 parts ethyl acetate as solvent. The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide. The vessel was then heated to 1 800C with stirring.

The pressure was brought up to 750 p.s.i.g. with ethylene. The pressure was maintained at 750 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide and the temperature was maintained at 1800C. After 1 hour of reaction, G.C. analysis of the reaction mixture showed that propionic acid was formed at the rate of 4.38 mols per liter per hour with all of the olefin reacted appearing as propionic acid.

Example 2 A pressure vessel as described in Example 1 was charged with 12 parts water, 12 parts ethyl iodide, 0.74 part nickel iodide (Nil2), 1.4 parts molybdenum hexacarbonyl, 14.4 parts lithium iodide, and 60 parts tetrahydrofuran as solvent.

The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide. Then the vessel was heated to 1 800C with stirring and the pressure was brought up to 800 p.s.i.g. with ethylene. The pressure was maintained at 800 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide and the temperature was maintained at 800 C. After 1 hour of reaction, G.C.

analysis of the reaction mixture showed propionic acid had been formed at the rate of 2.97 mols per liter per hour with all of the olefin reacting appearing as propionic acid.

Example 3 A pressure vessel as described in Example 1 was charged with 12 parts water, 12 parts iodoethane, 0.72 part nickel iodide (Nil2), 1.4 parts chromium hexacarbonyl, 14.3 lithium iodide and 60 parts tetrahydrofuran as solvent. The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide. The vessel was heated to 1 800C with stirring and the pressure was brought up to 900 p.s.i.g. using ethylene. The pressure was maintained at 900 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide.The temperature was maintained at 1 800C. After 1 hour of reaction, G.C. analysis of the reaction mixture showed propionic acid had been formed at the rate of 1.21 mols per liter per hour and that all of the olefin reacted had been converted to propionic acid.

Example 4 A magnetically-stirred pressure vessel with a glass liner was charged with 12 parts water, 12 parts ethyl iodide, 0.72 part nickel iodide (Nil2), 1.43 parts moiybdenum hexacarbonyl and 14 parts lithium iodide and 60 parts tetrahydrofuran as solvent. The vessel was swept out with argon and pressured to 300 p.s.i.g. with carbon monoxide. The vessel was then heated to 1 800C with stirring and the pressure was brought up to 750 p.s.i.g. with ethylene.The pressure was maintained at 750 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide and the temperature was maintained at 1 800 C. After 1 hour of reaction, G.C. analysis of the reaction mixture showed that propionic acid had been formed at the rate of 4.63 mols per liter per hour and that all of the olefin reacted had been converted to propionic acid.

Example 5 Example 4 was repeated with the exception that the molybdenum carbonyl was replaced with an equal amount of tungsten carbonyl. After 1 hour of reaction, G.C. analysis showed propionic acid had been formed at the rate of 2.6 mols per liter per hour and that all of the ethylene reacted had been converted to propionic acid.

Example 6 Using a reactor as described in Example 1, the vessel was charged with 11.4 parts water, 11.4 parts ethyl iodide, 0.7 part nickel iodide (Nil2),1.4 parts molybdenum hexacarbonyl, 18 parts lithium iodide, and 57 parts tetrahydrofuran as solvent.

The vessel was swept out with argon and was pressured with 100 p.s.i.g. of ethylene and then up to 600 p.s.i.g. with carbon monoxide. The vessel was then heated to 1 800C with stirring and the pressure was maintained at 750 p.s.i.g.

by recharging a 1:1 mixture of ethylene and carbon monoxide. The temperature was maintained at 1800 C. After 1/2 hour of reaction, G.C. analysis of the reaction mixture showed that propionic acid had been formed at the rate of 6.3 mols per liter per hour and that all of the ethylene reacted had been converted to propionic acid.

Example 7 A reactor as described in Example 1 was charged with 12 parts water, 1 2 parts ethyl iodide, 0.7 part nickel iodide, 1.4 parts molybdenum hexacarbonyl, 14 parts cesium iodide, and 60 parts tetrahydrofuran as solvent.

The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide and was heated to 1 800C with stirring. The pressure was raised to 900 p.s.i.g. using ethylene and the pressure was maintained at 900 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide. The temperature was maintained at 1 800 C. After 1 hour of reaction, G.C. analysis of the reaction mixture showed that propionic acid had been formed at the rate of 1.7 mols per liter per hour and that all of the ethylene reacted had been converted to propionic acid.

Comparative Example A Example 2 was repeated with the exception that no molybdenum was charged. After 1 hour of reaction, G.C. analysis showed that the rate of propionic acid formation was only 0.12 mol per liter per hour.

Example 8 A magnetically-stirred pressure vessel with a glass liner was charged with 68 parts propionic acid, 12 parts iodoethane, 0.8 part nickel iodide, 1.6 parts molybdenum hexacarbonyl, and 16 parts lithium iodide. The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide. The vessel was heated to 1 600C with stirring and the pressure was brought up to 800 p.s.i.g. with ethylene. The pressure was maintained at 800 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide and the temperature was maintained at 1 600C. After 50 minutes reaction.G.C. analysis of the reaction mixture showed propionic anhydride had been formed at the rate of 10 mols per liter per hour and that all of the ethylene reacted had been converted to propionic anhydride.

Example 9 A magnetically-stirred pressure vessel with a glass liner was charged with 68 parts propionic acid, 1.6 parts molybdenum hexacarbonyl, 0.8 part nickel iodide, 12 parts ethyl iodide and 16 parts lithium iodide. The vessel was swept out with argon and was pressured to 100 p.s.i.g. with hydrogen and then up to 500 p.s.i.g. with carbon monoxide. The vessel was heated to 1 800C with stirring. The pressure was brought up to 750 p.s.i.g. with ethylene and the pressure was maintained at 750 p.s.i.g. by recharging a 1:1 mixture of ethylene and carbon monoxide.The temperature was maintained at 1 800C. After 1 hour of reaction G.C. analysis of the reaction mixture showed that propionic anhydride had been formed at the rate of 7.1 mols per liter per hour and that all of the ethylene reacted had been converted to propionic an hydride.

Example 10 Example 8 was repeated with the exception that temperature maintained at 1400C and reacting was for 1 hour. G.C. analysis of the reaction mixture showed propionic anhydride had been formed at the rate of 3.2 mols per liter per hour and that all of the ethylene reacted had been converted to propionic anhydride.

Example 11 Example 9 was repeated with the exception that molybdenum hexacarbonyl was replaced with an equal amount of tungsten hexacarbonyl.

After 1 hour of reaction, G.C. analysis of the reaction mixture showed that propionic anhydride had been formed at rate of 1.8 mols per liter per hour and that all of the ethylene reacted had been converted to propionic an hydride.

Example 12 Example 9 was repeated with the exception that lithium iodide was replaced with an equal amount of potassium iodide. After 2 hours of reaction, G.C. analysis showed that propionic anhydride had been formed at the rate of 0.7 mols per liter per hour and that all of the ethylene reacted had been converted to propionic anhydride.

Example 13 Example 9 was repeated with the exception that lithium iodide was replaced with equal amount of cesium iodide. After 1 hour of reaction, G.C. analysis showed propionic anhydride formed at rate of 1.9 mols per liter per hour and that all of the ethylene reacted had been converted to propionic anhydride.

Example 14 Example 9 was repeated except that no hydrogen was charged after 1 hour of reaction.

G.C. analysis of the reaction effluent showed that propionic anhydride had been formed at the rate of 2.3 mols per liter per hour and that all of the ethylene reacted had been converted to propionic anhydride.

Comparative Example B Example 9 was repeated with the exception that no lithium iodide was charged. After one hour of reaction, G.C. analysis showed that propionic anhydride had been formed at rate of only 0.2 mol per liter per hour.

Comparative Example C Example 9 was repeated with the exception that no molybdenum hexacarbonyl was charged.

After 1 hour of reaction, G.C. analysis showed that propionic anhydride formed at rate of 0.5 mol per liter per hour.

Example 15 In this example, a magnetically-stirred Hastelloy Parr bomb with a glass liner was employed as the reaction vessel. The bomb was charged with tetrahydrofuran (57 parts), ethyl iodide (12 parts), nickel iodide (0.68 parts), molybdenum hexacarbonyl (1.4 parts), lithium iodide (13.6 parts) and methanol (16 parts), was swept out with argon and pressured to 400 p.s.i.g. with carbon monoxide. The vessel was heated to 1 800C with stirring and then the vessel was charged with ethylene to bring the pressure up to 800 p.s.i.g. The pressure was maintained at 800 p.s.i.g. by recharging carbon monoxide and ethylene in equal amounts when needed and the temperature was maintained at 1 800C. After 1/2 hour reaction. G.C. analysis of the reaction effluent showed that methyl propionate had been produced at the rate of 1.75 mols per liter per hour.

Example 16 Example 1 5 was repeated except that the molybdenum hexacarbonyl was replaced by an equal amount of tungsten hexacarbonyl. It was found that methyl propionate had been formed at the rate of 0.55 mol per liter per hour.

Example 17 Example 1 5 was repeated but the molybdenum hexacarbonyl was replaced by an equal quantity of chromium hexacarbonyl. Analysis showed that methyl propionate had been formed at the rate of 0.52 mol per liter per hour.

Comparative Example D Example 1 5 was again repeated but the molybdenum hexacarbonyl was omitted from the charge. Analysis showed that no methyl propionate had been formed.

Claims (10)

Claims

1. A liquid-phase carbonylation catalyst comprising a molybdenum-nickel-alkali metal, a tungsten-nickel-alkali metal, or a chromium nickel-alkali metal co-catalyst component and a halide component represented by the following formula: X:T:Z:Q, wherein X is molybdenum, tungsten or chromium T is nickel, X and T being in zero valent form or in the form of a halide, an oxide, a carboxylate of 1 to 20 carbon atoms, a carbonyl or a hydride;Z is a halide source which is hydrogen halide, halogen, an alkyl halide wherein the alkyl group contains 1 to 20 carbon atoms or an alkali metal halide, and Q is the alkali metal component and is in the form of an iodide, a bromide, a chloride or a carboxylate as defined for X and T, the molar ratio of X to T being 0.1-10:1, the molar ratio of X+T to Q being 0.1-10:1, and the molar ratio of Z to X+T being 0.01-0.1:1.

2. A catalyst as claimed in Claim 1, substantially as hereinbefore described with particular reference to the Examples.

3. A catalyst as claimed in Claim 1, substantially as illustrated in any one of the Examples.

4. A process for the preparation of a carboxylic acid, a carboxylic acid anhydride or a carboxylic acid ester, which comprises reacting an olefin with carbon monoxide in the presence of water, a carboxylic acid and/or an alcohol, in the presence of a halide, and in the presence of a catalyst, wherein the catalyst comprises a molybdenumnickel-alkali metal, a tungsten-nickel-alkali metal or a chromium-nickel-alkali metal co-catalyst component.

5. A process as claimed in Claim 5, wherein the co-catalyst component comprises molybdenumnickel-alkali metal.

6. A process as claimed in Claim 4 or Claim 5, wherein the alkali metal is lithium.

7. A process as claimed in any one of Claims 4 to 6 wherein the catalyst is as defined in any one of Claims 1 to 3.

8. A process as claimed in Claim 4, substantially as hereinbefore described with particular reference to the Examples.

9. A process as claimed in Claim 4, substantially as illustrated in any one of the Examples.

10. A carboxylic acid, carboxylic acid anhydride or carboxylic acid ester when prepared by the process claimed in any one of Claims 4 to 9.