JPS6327334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of acetic acid. More specifically, the present invention relates to a method for producing acetic acid from methyl formate, and specifically relates to a catalytic rearrangement reaction of methyl formate to acetic acid.

The conversion of methyl formate to acetic acid is a well known reaction. For example, US Pat. No. 2,508,513 states:
carbonyl-forming metal catalyst (one or more iron group metals,
A liquid phase process is described in which methyl formate is heated in the presence of nickel (preferably nickel) and a halogen. The use of nickel iodide hexahydrate and nickel carbonyl is exemplified. This method is carried out at high temperatures,
Although the yield is not reported, it is clear from the mention of by-products that the yield is relatively low. US Pat. No. 1,697,109 discloses a method for the gas phase conversion of methyl formate to acetic acid using acetate or a substance capable of producing acetate as a catalyst. Examples of catalysts with this property include copper, tin, lead,
There are compounds of zinc and aluminum. An example of the operation of this method is not shown. More recently, group noble metal-based catalysts have been disclosed for this reaction. For example, US Pat. No. 4,194,056 describes a method for producing acetic acid by heating methyl formate in the presence of a soluble rhodium salt and an iodine-containing promoter. Relatively high yields are reported, and the same specification also mentions cobalt iodide, cobalt iodide/triphenylphosphine, methyl iodide, copper chloride/triphenylphosphine, ferrous chloride/triphenylphosphine, enylphosphine,
It states that tungsten hexacarbonyl, rhenium pentacarbonyl and molybdenum hexacarbonyl are not catalysts for this reaction, with rhodium being the only satisfactory catalyst. Although rhodium gives good results, like all group noble metals it is a very expensive catalyst. US Pat. No. 3,839,428 shows the use of Group or Group B metal catalysts, but relatively high temperatures and pressures are used.

U.S. Patent Application No. 268029, filed by the applicant
No. 3, filed May 28, 1981, discloses that formic acid is Methods for carrying out methyl rearrangement or isomerization are described. This method, which involves a nickel catalyst,
It allows efficient rearrangement of methyl formate without the need for the use of noble metal catalysts, but
It would be useful to improve this reaction with respect to reaction rate and productivity without the need for organic promoters.

It is therefore an object of the present invention to provide an improved process for the production of acetic acid by rearrangement reaction of methyl formate, which requires neither high temperatures nor group noble metals, and without the need for the use of organic promoters and in a short process. The object of the present invention is to provide a method that makes it possible to produce acetic acid in high yield in a short reaction time.

In the present invention, the conversion of methyl formate to acetic acid is carried out in the presence of a halide (preferably iodide or bromide, especially iodide) and in the presence of carbon monoxide, molybdenum-nickel-alkali metal, chromium- This is carried out by using a nickel-alkali metal or tungsten-nickel-alkali metal cocatalyst. The surprising discovery made here is that under an environment of the nature shown here, the cocatalyst system of the present invention can produce methyl formate at relatively low temperatures and pressures, yet at a high rate and in high yields. It allows the rearrangement or isomerization of

The remarkable effectiveness of the catalyst system in the process of the invention is quite surprising in view of the experimental data described in EP-A-0035458. In the same specification, in the presence of a nickel catalyst, in the presence of an alkyl halide, an alkali metal halide, or an alkaline earth metal halide, and tetramethylene sulfone or a derivative thereof, or an alkyl ether of polyethylene glycol,
Alternatively, a method for producing acetic acid by carbonylating methanol in the presence of a solvent such as an amide is shown. The same specification states that in experiments using nickel with chromium, molybdenum, or tungsten, no reaction occurred even after two hours. It has also been observed that when nickel-based catalysts are commonly used in carbonylation reactions, the nickel component tends to volatilize and exit the reaction process as vapor. However, it has been observed with the catalyst system of the present invention that the volatility of nickel is surprisingly strongly suppressed, thus providing a highly stable catalyst combination.

Accordingly, in the present invention, formic acid is reacted in the presence of carbon monoxide, in the presence of a halide, such as a halogenated hydrocarbyl (especially a lower alkyl halide, such as methyl iodide), and in the presence of the aforementioned cocatalyst combination. Heat the methyl.

Carbon monoxide is removed in the gas phase and recycled if necessary. The normally liquid and relatively volatile components present in the final product mixture, such as alkyl halides, unreacted methyl formate and any by-products, are easily removed, e.g. by distillation, for recycling. They can be separated from each other and the final product obtained is essentially only the desired acetic acid. In the case of preferred liquid phase reactions, the organic compounds are easily separated from the metal-containing components, for example by distillation. The reaction is carried out successfully in a reaction zone into which carbon monoxide, methyl formate, halide, and cocatalyst are fed.

A wide range of temperatures, e.g. 25-350°C, are suitable for practicing the method of the invention, but
250°C is preferred, and a more preferred temperature is generally
In the range of 125-225℃. Lower temperatures can be used, but these tend to reduce the reaction rate; higher temperatures can also be used, but without any particular effect. The reaction time is also not a critical parameter of the process of the invention and is strongly dependent on the temperature used, but common residence times will, for example, generally be in the range from 0.1 to 20 hours. Although this reaction is carried out under superpressure, one advantage of the present invention is that, as mentioned above, extremely high pressures that would require special high pressure equipment are not required. Generally, this reaction is preferably at least 1.1 Kg/cm ²
Carbon monoxide partial pressure less than 140Kg/cm ² (2000psi) at (15psi), more preferably 1.1 to 70Kg/cm2
cm ² (15~1000psi), especially 2.1~14Kg/cm ² (30~
It is efficiently carried out by using a carbon monoxide partial pressure of 0.07 Kg/cm ² (1 psi) to 350 Kg/cm ² (5000 psi) or 700 Kg/cm ²
Carbon monoxide partial pressures up to (10,000 psi) can also be used. By setting the partial pressure of carbon monoxide to such a value, a suitable amount of carbon monoxide component will always be present. Of course, the total pressure is such as to provide the desired partial pressure of carbon monoxide, and preferably as necessary to maintain the liquid phase. If the liquid phase is maintained, the reaction can be carried out successfully in an autoclave or similar apparatus. After the desired residence time has elapsed, the reaction mixture is separated into several components, for example by distillation. that time,
Preferably, the reaction product is sent to a distillation zone. This distillation zone separates volatile components from the product acid,
and can be a fractionation column or series of columns effective to separate the acid from the less volatile catalyst compounds in the reaction mixture. The boiling points of the volatile components are sufficiently far apart that there is no problem in separating these components by well-known distillation. Similarly, relatively high boiling organic components can be easily separated by distillation from the metal catalyst components. The cocatalyst and halide component thus recovered can then be used to react with fresh methyl formate and carbon monoxide to produce additional amounts of acetic acid.

Although not required, the method can be carried out in the presence of a solvent or diluent. The presence of a relatively high boiling solvent or diluent, preferably the product acid itself, allows the use of lower total pressures. Alternatively, the solvent or diluent can be any organic solvent that is inert under the circumstances of the process, such as hydrocarbons (eg octane, benzene, toluene, xylene and tetralin) or carboxylic acids. When a carboxylic acid is used, acetic acid is preferred. This is because it is preferable that the solvent used be specific to the system. However, other carboxylic acids can also be used. As will be clear to those skilled in the art, if the solvent or diluent is not the product itself, it is best to choose one that has a boiling point sufficiently different from that of the desired product of the reaction mixture so that it can be easily separated. Appropriate.
Mixtures can also be used.

Carbon monoxide is preferably used in substantially pure form as commercially available, although inert diluents such as carbon dioxide, nitrogen, methane and noble gases can be used if desired. . The presence of an inert diluent does not affect the carbonylation reaction, but its presence requires increasing the partial pressure to maintain the desired carbon monoxide partial pressure. However, carbon monoxide, like other reactants, must be substantially dry. That is,
It is necessary that the CO and other reactants have a suitably low water content. However, the presence of small amounts of water that can be found in commercially available forms of the reactants is perfectly acceptable. Hydrogen that may be present as an impurity should not be excluded, but may instead tend to stabilize the catalyst. Indeed, in order to obtain a low CO partial pressure, the supplied CO can be diluted with hydrogen or any inert gas such as those mentioned above. Surprisingly, the presence of hydrogen does not result in the formation of reduction products. If necessary, a diluent gas, e.g. hydrogen, is generally around 95%
Up to an amount can be used.

The cocatalyst component can be used in any convenient form. For example, nickel, molybdenum, tungsten and chromium can be the metals themselves in finely divided form or organic or inorganic compounds effective to introduce these cocatalyst components into the reaction system. For example, representative compounds include carbonates, oxides, hydroxides, bromides, iodides, chlorides, oxyhalides, hydrides, lower alkoxides (methoxides), phenoxides, or Mo, W, Cr or Ni carboxylates ( The carboxylate ions are derived from alkanoic acids having 1 to 20 carbon atoms, such as acetate, butyrate, decanoate, laurate,
benzoate and others). Similarly, complexes of these cocatalyst components such as carbonyl and metal alkyls and chelates, associative compounds and enol salts can also be used. Examples of other complexes include bis(triphenylphosphine)nickel dicarbonyl, tricyclopentadienyltrinickel dicarbonyl, tetrakis(triphenylphosphite)nickel, and corresponding complexes of other components such as molybdenum hexane. Carbonyl and tungsten hexacarbonyl. Particular preference is given to compounds in elemental form as well as halides, especially iodide compounds, and organic salts, such as monocarboxylic acid salts corresponding to the acids formed.

Alkali metal components, i.e. metals of group a of the periodic table, such as lithium, potassium, sodium,
and cesium are suitably used as compounds, especially as salts, most preferably as halides, such as iodides. A preferred alkali metal is lithium. However, alkali metal components, as hydroxides, carboxylates, and alkoxides,
Alternatively, other convenient compound forms, such as those described above with respect to other cocatalyst components, may also be used.
Representative alkali metal compounds include, for example, sodium iodide, potassium iodide, cesium iodide,
Lithium iodide, lithium bromide, lithium chloride,
Lithium acetate and lithium hydroxide.

It should be understood that the foregoing compounds and complexes are merely illustrative of some suitable forms of cocatalyst components and are not intended to be limiting.

The specified cocatalyst components used may contain impurities normally associated with commercially available metals or metal compounds;
No further purification is necessary.

The amount of each cocatalyst component used is not critical at all and is not an important parameter of the process according to the invention and can therefore be varied within wide limits. As those skilled in the art will appreciate, the rate of reaction is affected by the amount of catalyst, so the amount of catalyst used will be such as to provide the appropriate and reasonable rate of reaction desired.
However, essentially any amount of catalyst promotes the basic reaction and can be considered a catalytically effective amount. Generally, however, each catalyst component is used in an amount of 1 mmol to 1 mol, preferably 15 mmol to 500 mmol, per liter of reaction mixture.
More preferably, amounts of 15 mmol to 150 mmol are used.

The ratio of nickel to molybdenum, tungsten, or chromium cocatalyst components can vary. Generally, 1 mole of nickel component is 0.01 to 100
moles of the second cocatalyst component, i.e. molybdenum, tungsten or chromium component, preferably 1 mole of nickel component is used for 0.1 to 20 moles of the second cocatalyst component, more preferably 1 mole of the second cocatalyst component. moles of nickel component to 1 to 10 moles of the second cocatalyst component. Similarly, the ratio of nickel to alkali metal component can be varied, for example 1 mole of nickel to 1 to 1000 mol of alkali metal component, preferably 10 to 1000 moles of alkali metal component.
It is used per 100 mol of alkali metal component, more preferably from 20 to 50 mol of alkali metal component.

The amount of iodide component can also vary widely, but generally the iodide component should be present in an amount of at least 0.1 mole per mole of nickel. Generally, from 1 to 100 moles of iodide are used per mole of nickel, preferably from 2 to 50 moles of iodide. Usually, no more than 200 moles of iodide are used per mole of nickel. However, it will be readily appreciated that the iodide component need not be added to the system as hydrocarbyl iodide, but rather as other organic iodide or hydrogen iodide or other inorganic iodide (such as salts, e.g. alkali metal salts or other It may be added as a metal salt) or even as elemental iodine. These things are
This also applies to the bromide component if bromide is used instead of iodide.

As mentioned above, the catalyst system of the present invention consists of an iodide component and a molybdenum-nickel-alkali metal, tungsten-nickel-alkali metal, or chromium-nickel-alkali metal cocatalyst component. The catalyst system of the present invention enables the production of acetic acid in high yields in short reaction times without the use of group noble metals, and due to the presence of alkali metal components together with molybdenum, tungsten or chromium components. , it is possible to obtain good results with relatively small amounts of cocatalyst components and small amounts of nickel compared to prior art processes using nickel-containing catalysts.

Molybdenum - nickel - alkali metal, tungsten - nickel - alkali metal or chromium -
A particular embodiment of a catalyst comprising a nickel-alkali metal cocatalyst component and an iodide component has the formula X:T:
Z: Can be represented by Q. where X is molybdenum, tungsten or chromium, T is nickel, and X and T are in the zero-valent form or in the form of a halide, oxide, carboxylate of 1 to 20 carbon atoms, carbonyl or hydride. It is. Z is an iodide source and is hydrogen iodide, iodine, an alkyl iodide in which the alkyl group contains 1 to 20 carbon atoms, or an alkali metal iodide, and Q is an alkali metal moiety. The preferred alkali metal is lithium, as described above, in the iodide or bromide or carboxylate form as indicated for X and T. The molar ratio of X to T is 0.1 to 10:1, the molar ratio of X+T to Q is 0.1 to 10:1, and the molar ratio of Z to X+T is 0.01 to 0.1:1. The iodide component can be replaced with bromide.

As can be readily seen, the foregoing reaction can easily be adapted to a continuous process, in which the reactants and catalyst are continuously fed to a suitable reaction zone and the reaction mixture is continuously distilled. to separate the volatile organic components to form a final product consisting essentially only of carboxylic acids and to recycle the other organic components and, in the case of liquid phase reactions, also to recycle the fraction containing residual catalyst. let

It will also be readily understood that, if necessary, the catalytic reaction according to the process of the invention can be carried out by suitably adjusting the total pressure in relation to the temperature so that the reactants are in the gas phase when they come into contact with the catalyst. By doing so, it can be carried out in the gas phase. In the gas phase process, and also in the liquid phase process, the catalyst components can be supported on a carrier, if necessary. That is, the catalyst components can be dispersed on supports of known types, such as alumina, silica, silicon carbide, zirconia, carbon, bauxite, attapulgus clay, and the like. The catalyst components can be dispersed onto the support by well known methods. For example, the catalyst components are dispersed by impregnating the carrier with a solution of the catalyst components.
The concentration relative to the carrier can vary widely, for example from 0.01 to 10% by weight or more. Typical working conditions in the gas phase process are:
The temperature is 100-350℃, preferably 150-275℃, more preferably 175-255℃, and the pressure is 0.07-350℃.
350Kg/ ^cm2 (1~5000psia), preferably 4.1~105
Kg/ ^cm2 (59-1500psia), more preferably 10.5
~35Kg/ ^cm2 (150~500psia), and the space velocity is
50 to 10,000 hr ^-1 , preferably 200 to 6,000 hr ^-1 , and more preferably 500 to 4,000 hr ^-1 (values at standard temperature and pressure). In the case of carrier-supported catalysts, the iodide component is included in the reactants rather than dispersed on the carrier.

The examples presented below will help to understand the invention more fully. However, these examples should be construed as illustrative only and not as limiting the invention. In the examples, all parts are by weight unless otherwise specified.

Example 1 In a 1 liter Parr autoclave were added 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. I loaded it. The reactor was flushed three times with 4.5 Kg/cm ² (50 psig) of carbon monoxide and then 5.9 Kg/cm ²
(70 psig) of hydrogen and 17.1 Kg/cm ² (230 psig) of carbon monoxide. The reactor was then heated to 200°C and maintained at this temperature for 3 hours. after that,
The contents of the reactor were removed and analyzed by gas chromatography. As a result of analysis, the reaction mixture contained a net amount of 100 parts of acetic acid, unreacted methyl formate,
It contained methyl iodide, along with the catalyst components and the initially charged acetic acid.

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 were charged. The reactor was flushed three times with 4.5 Kg/cm ² (50 psig) carbon monoxide, then 5.9 Kg/cm ² (70 psig)
of hydrogen and ⁴⁵⁰ psig of carbon monoxide. The reactor was then heated to 200°C and
This temperature was maintained for 5 hours. The contents of the reactor were then removed and analyzed by gas chromatography. Analysis showed that the reaction mixture contained a net yield of 127 parts of acetic acid, along with unreacted methyl formate, methyl iodide, catalyst components, and the initial acetic acid charge.

Example 3 Into the autoclave of Example 1, 150 parts of methyl formate, 100 parts of methyl iodide, 100 parts of acetic acid, 7.5
part of nickel iodide, 15 parts of chromium carbonyl,
and 60 parts of lithium iodide. The reactor was flushed three times with 4.5 kg/cm ² (50 psig) of carbon monoxide and then flushed with 5.9 kg/cm ² (70 psig) of hydrogen and 17.1 kg/cm ² (230 psig) of carbon monoxide. I pressed. The reactor was then heated to 200°C and maintained at this temperature for 3 hours. The contents of the reactor were then removed and analyzed by gas chromatography. Analysis showed that the reaction mixture contained a net yield of 123 parts of acetic acid, along with unreacted methyl formate, methyl iodide, catalyst components, and the initially charged acetic acid.

Example 4 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 tungsten hexacarbonyl, and 60 parts of lithium iodide were charged. The reactor was flushed three times with 4.5 Kg/cm ² (50 psig) carbon monoxide and then 5.9 Kg/cm ²
(70 psig) of hydrogen and 31.1 Kg/cm ² (430 psig) of carbon monoxide. The reactor was then heated to 200°C and maintained at this temperature for 5 hours. after that,
The contents of the reactor were removed and analyzed by gas chromatography. As a result of analysis, the reaction mixture contained a net amount of 100 parts of acetic acid, unreacted methyl formate,
It contained methyl iodide, along with the catalyst components and the initially charged acetic acid.

Example 5 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 hexacarbonyl, and 60 parts of lithium iodide were charged. The reactor was flushed three times with 4.5 Kg/cm ² (50 psig) carbon monoxide and then 36 Kg/cm ²
Pressurized with carbon monoxide (500 psig). The reactor was then heated to 200°C and maintained at this temperature for 5 hours. The contents of the reactor were then removed and analyzed by gas chromatography. Analysis revealed that the reaction mixture contained a net yield of 149 parts of acetic acid along with unreacted methyl formate, methyl iodide, catalyst components, and the initially charged acetic acid. Substantially all of the methyl formate charge was converted.

Claims (1)

[Claims] 1. Heating methyl formate with carbon monoxide in the presence of a molybdenum-nickel-alkali metal, tungsten-nickel-alkali metal, or chromium-nickel-alkali metal cocatalyst component and in the presence of iodide or bromide. A method for producing acetic acid, comprising the steps of: 2. The method of claim 1, wherein the cocatalyst comprises molybdenum-nickel-alkali metal. 3. The method according to claim 1, wherein the alkali metal is lithium. 4. The method of claim 3, wherein the cocatalyst comprises molybdenum-nickel-lithium.