FR2540863A1 - PROCESS FOR THE PREPARATION OF ACETIC ACID BY CATALYTIC TRANSPOSITION OF METHYL FORMAT - Google Patents

Abstract

PROCESS FOR PREPARING ACETIC ACID BY CATALYTIC TRANSPOSITION OF METHYL FORMIATE. METHYL FORMIATE IS HEATED IN THE PRESENCE OF CARBON MONOXIDE, USING A CO-CATALYST BASED ON MOLYBDENE-NICKEL-ALKALINE METAL OR TUNGSTENE-NICKEL-ALKALINE METAL, AND IN THE PRESENCE OF IODIDE OR BROMIDE. THE PROCESS USES NO HIGH TEMPERATURES, NOBLE METALS OF GROUP VIII, OR ORGANIC PROMOTERS. THE ACETIC ACID OBTAINED CAN BE USED AS A SOLVENT OR AN INTERMEDIATE OF SYNTHESIS.

Description

The present invention relates to the preparation of acetic acid and more

especially, production

  acetic acid from methyl formate, specifically

  the catalytic transfer of methyl formate to acetic acid. Transformation of methyl formate to acetic acid is a known reaction US Pat. No. 2,508,513, for example, describes a liquid phase process in which

  the methyl formate is heated in the presence of a catalyst

  carbonyl-forming metal and in the presence of halogen, the catalyst being defined as being based on

  of one or more of the metals of the iron family, preferably

  Nickel is used as an example.

  hexahydrate nickel iodide and nickel carbonyl.

  The process is carried out at elevated temperature and

  although no mention is made of yields, it is apparent from the reference

  to by-products that these yields are relative-

  The patent US-A-1 697 109 discloses the

  vapor phase formation of methyl formate into acetic acid

  when substances used as catalysts

  which are acetates or capable of forming acetates.

  Examples illustrating catalysts of this nature are compounds of copper, tin, lead, zinc and aluminum. The document does not describe any examples of the implementation of the process. More recently, catalysts based on Group VIII noble metals have been described for this reaction. Thus, US Pat. No. 4,194,056 shows the preparation of acetic acid by heating methyl formate in the presence of a soluble salt of rhodium and a

  promoter containing iodine.

  relatively high, and this patent indicates that cobalt iodide, cobalt iodide / triphenyl phosphine,

  methyl iodide, copper chloride / triphenyl phos-

  phine, ferrous chloride / triphenyl phosphene, tungsten hexacarbonyl, rhenium pentacarbonyl and molybdenum

  hexacarbonyl are not catalysts for this reaction.

  rhodium being the only satisfactory catalyst.

  If rhodium gives good results, it is a catalyst

  very expensive, like all the noble metals of group VIII.

  U.S. Patent No. 3,839,428 uses as catalyst metals

  Group VIII or Group IIB, but it applies

  eratures and relatively high pressures. In the French patent application No. 82 09 301, the

  Applicant describes a process of transposition or isomerism

  methyl formate using a non-noble metal catalyst system comprising a molybdenum-nickel or tungsten-nickel co-catalyst component and a promoter which is an organic phosphorus compound or a compound organic nitrogen This process, which involves a nickel-based catalyst, allows an effective transposition of methyl formate without requiring the implementation of a noble metal catalyst it is useful to improve the reaction in terms of speed of reaction and productivity without the need to appeal

organic promoters.

  One of the objects of the present invention is therefore to provide an improved process for the manufacture of acetic acid by transposition of methyl formate, a process which does not require high temperatures or noble metals of group VIII and which allows the production of of acetic acid, obtained in high yields and short reaction times without the need to use organic promoters. According to the invention, the transformation of the

  methyl formate to acetic acid using a

  molybdenum-nickel-alkali metal type catalyst, such as

  chrome-nickel alkali metal or tungsten-nickel-type

  alkali metal, in the presence of a halide which suitably is an iodide or a bromide, especially an iodide,

  and in the presence of carbon monoxide (or carbon monoxide).

  It has been surprisingly found that this cocatalyst system, in an environment of the indicated nature, allows the transposition or isomerization of methyl formate not only at relatively low temperatures and pressures but with

  fast and high-yielding acetic acid.

  The remarkable efficiency of the catalyst system of the process of the present invention is particularly surprising when one refers to the experimental data cited in European Patent Application Publication No. 0 035 458, which describes the carbonylation of methanol to produce the acetic acid in the presence of a nickel catalyst, an alkyl halide, an alkaline halide

  or alkaline earth, and a solvent which is a tetramethyl-

  Sulfone or its derivative or an alkyl ether ether of a polyethylene glycol or an imide In this publication, it is stated that experiments made using nickel in combination with chromium, molybdenum or tungsten have shown absolutely no no evidence of reaction even after 2 hours It has also been observed that when conventional catalysts are

  of nickel in carbonylation reactions, there is a tendency

  It is surprising that, with the catalyst system of the present invention, the volatility of the nickel is strongly suppressed and it is not surprising that gets a combination

catalysts with high stability.

  Thus, according to the invention, methyl formate is heated in the presence of carbon monoxide, in the presence of a halide, for example a hydrocarbyl halide, especially a lower alkyl halide such as methyl iodide, and in the presence of the cocatalyst combination

which has been identified above.

  The carbon monoxide is removed in the vapor phase and, if desired, recycled. The normally liquid constituents can be easily removed and separated from each other, for example by distillation for recycling.

  and relatively volatile constituents, such as a halogen

  alkyl ester, unmodified methyl formate and any by-products possibly present in the final product mixture, and the net product yield is almost exclusively constituted by the desired acetic acid In the case of the liquid phase reaction preferably, organic compounds are readily separated, for example by distillation, from the metal-containing components. The reaction is suitably carried out in an area

  in which the carbon monoxide is introduced.

  bone, methyl formate, halide and cocatalyst

  sor. In the implementation of the process of the invention, a wide range of temperatures, for example between 350 ° C and 350 ° C, is suitable, but it is preferred to use

  temperatures between 100 and 2500 C and the temperatures

  The most preferred temperatures are between 125 and 2250 C. Temperatures lower than those mentioned can be used, but they tend to lead to reduced reaction rates, and higher temperatures can also be applied. there is no advantage

  The reaction time is not equal.

  not a parameter of the process and this time depends to a large extent on the temperature used, but it can be indicated, by way of example, that typical

  stay will generally be between 0.1 and 20 hours.

  The reaction is carried out at a pressure above atmospheric pressure but, as previously mentioned, a characteristic of the invention is that excessively high pressures, which require

  special for high pressures, are not essential.

  In general, the reaction is efficiently carried out using a partial pressure of carbon monoxide which is preferably at least 0.1 M Pa but less than 13.8 M Pa, more preferably between 0.1 and 6.9 M Pa and in particular between 0.2 and 1.4 M Pa, although one can also use partial pressures of CO between 6.9 k Pa and 34.5 or even 69 M Pa By establishing the partial pressure of carbon monoxide at the specified values, we guarantee

  the constant presence of adequate quantities of this con-

  Of course, the total pressure is the one

  will provide the desired partial pressure of carbon monoxide

  and, preferably, that required to maintain the existing

  In this case, the reaction can be advantageously carried out in an autoclave or in a similar apparatus. At the end of the desired residence time, the reaction mixture is distilled off, for example by distillation. its various constituents Preferably, one

  introduced the reaction product into a distillation zone

  which may be a column, or series of columns, of fractional distillation which can effectively separate the volatile constituents of the acid produced and separate the acid produced from the less volatile compounds of the catalyst

  of the reaction mixture The boiling points of the

  volatile substances are sufficiently far apart for the

  separation of these constituents by conventional distillation.

  In addition, the higher boiling point organic constituents can be easily distilled off to separate them from the metallic catalyst components. The cocatalyst thus recovered, as well as the halide component, can then be distilled off. combined with fresh amounts of methyl formate and carbon monoxide and reacted to produce additional amounts of acid

acetic.

  Although it is not essential, the process

  may be carried out in the presence of a solvent or diluent.

  The presence of a solvent or diluent with a high boiling point

  tion, preferably the product acid itself, will allow the use of more moderate total pressures.

  the solvent or diluent can be any organic solvent

  which is inert in the process environment, such as hydrocarbons, eg octane, benzene,

  toluene, xylene and tetralin, or carboxylic acids

  If a carboxylic acid is used, acetic acid is preferably chosen since it is preferred that the solvent used be a particular solvent in the system,

  although other carbohydrates may also be used

  When it is not a question of the product itself, a solvent or diluent having a boiling point which differs sufficiently from that of the desired product present in the reaction mixture to allow easy separation, is suitably selected. will appear to the man from

  Occupation Mixtures of solvents or diluents can be used.

  Carbon monoxide is preferably used in substantially pure form as it is available in the

  trade, but inert diluents such as carbon dioxide

  carbon (carbon dioxide), nitrogen, methane and rare or noble gases may be present, if desired The presence of inert diluents does not affect the carbonylation reaction, but this presence requires to increase the pressure The presence of minor amounts of water, as can be found in commercial forms of reactants, is, however, entirely acceptable. Hydrogen, which may be present under impurity, raises no objections and may even tend to stabilize the catalyst. In fact, to obtain low partial pressures of CO, the CO introduced can

  be diluted with hydrogen or any inert gas

  te such as those mentioned above It was found, surprisingly, that the presence of hydrogen does not cause

  formation of reduction products The gas used to dilute

  tion, for example hydrogen, can generally be used in an amount of up to about 95%, if

the desire.

  The components of the cocatalyst can be used in any convenient form. For example, nickel, molybdenum, tungsten and chromium can be used as metals themselves finely divided, or a compound, both organic and mineral,

  who can effectively introduce these constituents of the co-

  catalyst in the reaction system Thus, typical compounds include a carbonate, oxide, hydroxide, bromide,

7 2540863

  iodide, chloride, oxyhalogenide, hydride, lower alkoxide

  (methoxide), phenate or carboxylate of Mo, W, Cr or

  Ni, in which the carboxylate ion is derived from an alkaline

  with 1 to 20 carbon atoms, such as acetates, butyrates, decanoates, laurates, benzoates and similar acids.

  Likewise, complexes of these constituents can be used.

  Examples of other complexes include bis (triphenylphosphine) -nickel dicarbonyl, tricyclopentadienyl, co-catalyst, for example carbonyls and alkyl-metals as well as chelates, combination compounds, and enol salts. trinickel dicarbonyl, tretrakis (triphenylphosphite) nickel, and corresponding complexes of the other constituents, such as molybdenum hexacarbonyl and tungsten hexacarbonyl. Elemental forms, compounds which are halides, especially iodides, and organic salts, are particularly preferred. example of the salts of monocarboxylic acid

  corresponding to the acid that is produced.

  The metal component is suitably used

  alkali, for example a metal of group IA of the Periodic Table.

  Like lithium, potassium, sodium and cesium, in the form of a compound, particularly a salt and more preferably a halide, for example an iodide. The preferred alkali metal is lithium. However, it is also possible to use the alkali metal component. in the form of a hydroxide, carboxylate, alkoxide or in the form of other convenient compounds as mentioned above with respect to other components of the cocatalyst, and typical examples of alkali metal constituents are sodium iodide, potassium iodide, cesium iodide, lithium iodide, lithium bromide, lithium chloride, lithium acetate and lithium hydroxide It goes without saying that the compounds and complexes mentioned

  above are cited for illustrative purposes only.

  suitable constituents of the various components of the co-catalyst and that these quotations are not limiting. The specified constituents of the cocatalyst used may contain normally associated impurities.

  to the metal or metal compounds available in the

  merce, and it is not necessary to purify them further.

  The amount of each co-catalyst component used is by no means fundamental and does not constitute a parameter of the process of the invention. This amount can vary over a wide range. As the man of the art knows well, the amount of catalyst that we use

  is that of ensuring reasonable and suitable speed

  read, since the rate of reaction is

  the influence of the amount of catalyst However, essen-

  virtually any amount of catalyst will facilitate

  However, each component of the catalyst is used in an amount of 1 millimole to 1 mole, preferably 15 millimoles to 500 millimoles, and still more preferably 15 millimoles to 150 millimoles. ,

per liter of reaction mixture.

  The ratio of nickel to molybdenum, tungsten or

  chromium forming a constituent of the cocatalyst can vary.

  Typically, this ratio is one mole of the nickel component for 0.01 to 100 moles of the second cocatalyst component, namely the molybdenum, tungsten or chromium component, and

  the nickel component is preferably used in a quantity

  1 mol to 0.1 to 20 mol, more preferably 1 mol to 1 to 20 mol of the second co-catalyst component. Similarly, the ratio of nickel to alkali metal component may vary, for example 1 mol of nickel for 1 to 1000 moles of the alkali metal component, preferably for 10 to 100 moles and more preferably for 20 to 50 moles of the alkali metal. The amount of the iodide component may also vary widely, but in general this component must be present in an amount of at least 0.1 mole (expressed as I) per mole of nickel. Typically 1 to 100 moles of carbon are used. iodide,

  preferably 2 to 50 moles of the iodide, per mole of nickel.

  Ordinarily, no more than 200 moles of iodide are used per mole of nickel. However, it is self-evident that it is not necessary to add the iodide component in the form of a hydrocarbyl iodide but it can be supplied in the form of another organic iodide or in the form of iodohydrate or other inorganic iodide, for example a salt such as an alkali metal salt or another metal salt, or even in the form of elementary iodine The above also applies to a bromide component when the iodide is

replaced by a bromide.

  As previously mentioned, the catalyst system of the present invention comprises an iodide component

  and a molybdenum-based cocatalyst component

  nickel-alkali metal, tungsten-nickel-alkali metal or chromenickel-alkali metal The catalyst system

  of the present invention allows the production of acetic acid.

  that is obtained with high yields in short reaction times without the use of noble metals of group VIII, and the presence of the alkali metal constituent as well as the constituent molybdenum, tungsten, or chromium

  achieves good results with relative quantities.

  weak constituents of the cocatalyst and with reduced amounts of nickel compared to

  prior art involving a nickel-containing catalyst.

  A particular embodiment of the catalyst comprising the molybdenum-nickel-metal component

  alkali, tungsten-nickel-alkali metal or chromium-nickel-

  alkali metal of cocatalyst and the iodide component may be represented by the following formula

X: T: Z: Q,

  in which X represents molybdenum, tungsten or chromium, T represents nickel, X and T being in the form of zero valence (or valence) or in the form of a halide, an oxide, a carboxylate having 1 to carbon atoms, a carbonyl or a hydride; Z

  is a source of iodine or iodide which is a hydroiodic iodide

  iodine, an alkyl iodide in which the alkyl group contains 1 to 20 carbon atoms or an iodide of

2540863

  alkali metal, and Q is the alkali metal component The preferred alkali metal is lithium, as previously indicated, and is then in the form of an iodide or a bromide or a carboxylate, as defined for X and T, the molar ratio of X to T being between 0.1 and 10: 1, the molar ratio of (X + T) to Q being between 0.1 and 10: 1, and the molar ratio of Z to (X + T) being understood

  between 0.01 and 0.1: 1 The iodide component may be substituted

made by a bromide.

  It will be apparent that the reaction described above is easily amenable to continuous operation during which the bodies intended for

  react and the catalyst in the appropriate reaction zone.

  required and the reaction mixture is continuously distilled

  the remaining organic components are recycled and, in the case of a liquid phase reaction, a fraction containing residual catalyst being

also recycled.

  It will also appear that the catalytic reaction involved in the process of the invention can be carried out in the vapor phase, if desired, by a

  the total pressure correlated with the temperature

  erature, so that the bodies intended to react are

  in the form of steam when they come into contact with

  In the case of vapor phase operation, and in the case of liquid phase operation if desired, the catalyst components may be supported, i.e. they may be dispersed on a support of a conventional type such as alumina, silica, silicon carbide, zirconium oxide, carbon or carbon, bauxite, attapulgite and an analogous material catalyst components can be applied to the supports in a conventional manner, for example by impregnating the support with a solution of the catalyst component. The concentrations on the support can vary widely, for example between 0.01% by weight and 10% by weight. weight or more Conditions

  typical of vapor phase operation are a temperature

  1000 to 350 ° C, preferably 150 to 275 ° C and more preferably 1750 to 2250 ° C, an absolute pressure of 6.9 k Pa to 34.5 M Pa, preferably 0.4 to 10.35 M Pa and still more preferably 1 to 3.45 M Pa, with space velocities of 50 to 000 hours, preferably 200 to 6000 hours and even more preferably 500 to 4000 hours -1 (under normal conditions

  temperatures and pressures) In the case of a catalytic

  If it is supported, the iodide component is introduced with the bodies intended to react and it is not on the support. The following examples will serve to allow a more complete understanding of the invention) but it goes from

  they are provided for illustrative purposes only and

  In the examples, and except

  otherwise, all parts are by weight.

EXAMPLE 1

  In a Parr autoclave of one liter capacity, 150 parts of methyl formate, 100 parts of methyl iodide, 101 parts of acetic acid, 7.5

  parts of nickel iodide, 15 parts of molybdenum carbonyl

  and 60 parts of lithium iodide The reactor is swept three times with carbon monoxide (0.35 M Pa) and the reactor is then pressurized with hydrogen (0.48 M Pa) and Carbon monoxide (1.59 M Pa) is then heated to 2000 C and maintained at this temperature for 3 hours.

  reactor and analyzed by gas chromatography.

  The analysis shows that the reaction mixture contains a net production of 100 parts of acetic acid as well as unreacted methyl formate, methyl iodide, the constituents of the catalyst and the introduced acetic acid.

originally.

EXAMPLE 2

  In the autoclave of Example 1, 150 parts of methyl formate, 100 parts of methyl iodide, 100 parts of acetic acid, 7.5 parts of nickel iodide, 15 parts of molybdenum carbonyl and 60 parts of cesium iodide The reactor is swept three times with carbon monoxide (0.35 Il Pa), then it is put under pressure by introducing hydrogen (0.48 M Pa) and Carbon monoxide (3.1 14 Pa) The reactor is then heated to 2000 ° C. and maintained at this temperature for hours. The contents of the reactor are then removed and analyzed by gas chromatography. that the reaction mixture contains a net production of 127 parts of acetic acid as well as unmodified methyl formate, methyl iodide, the constituents

  catalyst and acetic acid originally introduced.

EXECUTIVE 3

  150 parts of methyl formate, 100 parts of methyl iodide, 100 parts of acetic acid, 7.5 parts of nickel iodide, 15 parts of chromium carbonyl and 60 parts of methyl iodide are introduced into the reactor of Example 1. parts of lithium iodide The reactor is swept three times with carbon monoxide (0.35 K Pa) and then pressurized with hydrogen (0.48 M Pa) and carbon monoxide (1 , 59 M Pa) Then the reactor is heated up to 2000 C and maintained at this temperature for 3 hours.

  then the contents of the reactor and analyzed by chroma-

  The analysis shows that the reaction mixture contains a net production of 123 parts of acetic acid as well as unreacted methyl formate, methyl iodide, catalyst constituents and

  acetic acid originally introduced.

EXAMPLE 4

  In the parr autoclave of one liter capacity of Example 1, 150 parts of methyl formate, 100 parts of methyl iodide, 100 parts of

  acetic acid, 7.5 parts of nickel iodide, 15 parts of tungsten

  Hexacarbonyl stear and 60 parts of lithium iodide The reactor is scavenged three times with carbon monoxide

13 2540863

  (0.35 M Pa) and then pressurized with hydrogen (0.48 M Pa) and carbon monoxide (2.96 M Pa). Then the reactor was heated up to 200 ° C. and maintained at this temperature for 5 hours. The contents of the reactor are then removed and analyzed by chromatography.

  The analysis shows that the reaction mixture

  has a net production of 100 parts of acetic acid, as well as unmodified methyl formate, methyl iodide, catalyst components and acetic acid

originally introduced.

EXAMPLE 5

  In the parr autoclave of one liter capacity, of Example 1, 150 parts of methyl formate, 100 parts of methyl iodide, 100 parts of acetic acid, 7.5 parts of nickel iodide, 15 parts

  of molybdenum hexacarbonyl and 60 parts of lithium iodide.

  The reactor is swept three times with carbon monoxide (0.35 M Pa) and then pressurized with carbon monoxide (3.45 M Pa).

  2000 C and maintained at this temperature for 5 hours.

  The contents of the reactor are then removed and analyzed by gas chromatography. The analysis shows that the reaction mixture contains a net production of 149 parts of acetic acid as well as methyl formate.

  unaltered methyl iodide, the constituents of

  lyser and acetic acid originally introduced There was an essentially complete transformation of the formate

of methyl introduced.

  It goes without saying that, without departing from the scope of the invention, many modifications can be made to the catalytic process for preparing acetic acid, described above.

Claims (4)

  1 Process for the preparation of acetic acid,   It is preferred that methyl formate be heated with carbon monoxide in the presence of a catalyst comprising a molybdenum-nickel-alkali metal or tungsten-nickel-alkali metal cocatalyst component, and presence of an iodide or bromide.   Process according to Claim 1, characterized in that the cocatalyst comprises molybdenum-nickel-metal alkaline.   Process according to Claim 1, characterized in   what the alkali metal is lithium.   Process according to Claim 3, characterized in   the co-catalyst is or comprises molybdenum-nickel- lithium.