JPS5839810B2 - Production method of acetic anhydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acetic anhydride by reacting methyl acetate or dimethyl ether with carbon monoxide.

More specifically, a method for producing acetic anhydride by reacting methyl acetate or dimethyl ether with carbon monoxide in the presence of nickel or a nickel compound component, a bromide or iodide halide, and an organic nitrogen group compound containing phosphorus or nitrogen. Lithium, as co-catalyst in
The use of one or more metals selected from aluminum and tin or their compounds, or the combination of these with one or more metals of Group 1 [A] of the periodic table or compounds of these metals. The present invention relates to a method for producing acetic anhydride, characterized by the following.

Conventionally, methods for producing carboxylic acid anhydrides by the reaction of carboxylic acid esters, ethers, and carbon monoxide include (a) using Group II noble metals, mainly rhodium, halides, and other third components as catalysts; Methods (Japanese Patent Publication No. 52-3926, JP-A-51-65709, JP-A-51-115403, etc.) (b) A method using nickel (or cobalt), a halide, and other third components as a catalyst (this method Japanese Patent Application Laid-Open No. 54-5921 filed by the inventors
No. 4, JP-A-52-78814, JP-A-52-788
No. 15, U.S. Pat. No. 2,729,651, etc.) are known.

However, rhodium used as a catalyst in the former method (a) is an extremely expensive substance (for example, Hy
drocarbnm pro-cossing 54.
June 83 (1975)), and during industrial implementation, rhodium complexes are prevented from being reduced to metal in a reducing atmosphere (Chemistry and Industry, 29 (5), p. 376 (1).
975)) or by distillation separation of the product, etc.
Special measures are required to prevent it from volatilizing and escaping from the reaction system (Japanese Unexamined Patent Publication No. 53-90204).

In contrast to the method using this expensive noble metal, the present inventors previously disclosed a method using a catalyst system using nickel in Japanese Patent Laid-Open No. 5459214.

That is, the latter method (b) represented by JP-A-54-59214 or U.S. Pat. Continuing intensive research with the aim of further increasing the reaction rate, we found that one or two selected from lithium, aluminum, and tin were added as a cocatalyst to a catalyst consisting of nickel and a halide, and an organic nitrogen group compound containing phosphorus or nitrogen. Using one or more metals or compounds of the metals, or cocatalysts with these metals and No. 1IA of the periodic table.
The present invention was accomplished by discovering a catalyst system that uses a cocatalyst system that uses one or more metals of the group 1 or 2 or more metals or compounds of these metals.

That is, the present invention provides monoxide with methyl acetate or dimethyl ether in the presence of (al) a nickel or nickel compound component, (a2) a halide that is a bromide or iodide, and (a3) an organic nitrogen group compound containing phosphorus or nitrogen. (b) Using one or more metals selected from lithium, aluminum, and tin or a compound of the metals as a cocatalyst in the method of producing acetic anhydride by reacting carbon, or using these cocatalysts. This is a method for producing acetic anhydride, characterized in that one or more metals of Group 11A of the periodic table or compounds of the metals are used in combination.

As the (al)nickel or nickel compound component used as the main catalyst metal in the present invention, organic or inorganic nickel compounds can be used.

For example, nickel compounds such as nickel powder, nickel acetate, nickel iodide, nickel acetylacetone, nickel tetracarbonyl, nickel dicarbonyl, nickel dicarbonylbistriphenylphosphine, and tetramethylammonium nickel iodide components are used.

Preferred (a2) halides for use with the nickel or nickel compound component are bromides or iodides or mixtures thereof.

Usually, the halides are used mostly in the form of alkyl halides such as methyl iodide, acid halides such as acetyl iodide, hydrogen halides such as hydrogen iodide, or any mixture thereof. can be introduced into the reaction solution as is.

Furthermore, it is also effective to introduce into the reaction solution a substance that generates any one or more of these halides, ie, argyl halides, acid halides, or hydrogen halides.

Substances that react with other components in the reaction solution to produce alkyl halides, acid halides, or hydrogen halides include inorganic halides, such as alkali metal halides such as lithium, sodium, and potassium, and magnesium; Alkaline earth metal halides such as calcium or metal halides such as aluminium, zinc, copper, lanthanum or cerium etc. and bromine or iodine, in the case of lithium, aluminium, tin, group 11A metal halides; It is also used as a co-catalyst, which will be described later.

Among the halides mentioned above, it is a particularly preferred embodiment to use methyl halides such as methyl iodide from the viewpoint of corrosion resistance of the reactor or separation and purification of reaction products.

In the present invention, (a3) an organic nitrogen compound containing phosphorus or nitrogen is used in combination with the above nickel component and halide.

Non-limiting examples of effective organic nitrogen group compounds are classified into groups.

(I) Trivalent organic nitrogen compound (4) An organic nitrogen group compound represented by the general formula M=- (where 1 represents N and P.

)(a) R1t R2t A compound in which R3 represents hydrogen or a saturated alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group, each of which may be the same or different from each other M=N Monomethylamine, dimethylamine, trimethylamine , monoethylamine, diethylamine, triethylamine, dimethylethylamine, tri-n-propylamine, tri-1so-propylamine, tri-n-butylamine, tri-tert-butylamine, aniline, dimethylaniline, diethylaniline, dimethylbenzylamine, toluidine, triphenylamine, Amines such as cyclohexylamine.

M=P phosphines such as tri-n-propylphosphine, tri-1so-propylphosphine, tri-n-butylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine, and triphenylphosphine.

(b) A compound in which R1 represents hydrogen or a saturated alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group, and R2tRs is connected to a polymethylene group having 1 to 5 carbon atoms.

Cyclic compounds such as pyrrolidine, N-methylpyrrolidine, piperidine, N-phenylpiperidine, etc. (c) R1 and R2 represent hydrogen, a saturated alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group, and each may be the same or the other may be different.

R3 is a compound representing a saturated aliphatic acyl group having 1 to 10 carbon atoms, R1 is hydrogen or a saturated alkyl group, cycloalkyl group, or aryl group having 1 to 10 carbon atoms, and R2
, R3 is a lactam compound in which R3 is linked with a carboxypolymethylene group.

Carboxylic acid amides such as acetamide, N,N-dimethylacetamide, acetanilide, N-methyl-N-phenylacetamide, and lactams such as N-methyl-pyrodinone.

(d) A compound in which at least one of R1, R2, and R3 is a carboxymethyl group, and the remainder represents hydrogen, a saturated alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group, which may be the same or different.

Carboxylic acid derivatives such as N,N dimethylglycine, N,N-di-ethylglycine, iminodiacetic acid, N-methyldiiminoacetic acid, nitrilotriacetic acid.

(B) An organic nitrogen group compound represented by the general formula R-C3N (where R represents an alkyl group, a cycloalkyl group, or an aryl group having 1 to 10 carbon atoms).

) Acetonitrile, propionitrile, penzoni l-I
Nitriles such as J.

RI R3 (q General formula >Ml-R5-M2<.

An organic nitrogen group compound represented by (however, M149M2 is N t P, and ○(a
) R1, R2, R3, R4 are hydrogen or carbon number l~
10 saturated alkyl groups, cycloalkyl groups, or aryl groups, and R3 is a polymethylene group having 1 to 10 carbon atoms, a phenylene group, or a carbonyl group.

Ml, M2=N, P ethylene bis(diphenylphosphine), phenylene bis(dimethylphosphine), N, N, N', N'-tetramethylethylenediamine, N, N, N', N'-tetraethylethylenediamine, N, N, N', N'-tetra-n-propylethylenediamine, N, N, N',
N'-tetramethylmethylenediamine, N, N, N',
N'-tetramethyl urine L Compounds such as N-methyl-2-pyrodinone and triethylenediamine.

(b) R1 and R3 are hydrogen, a saturated alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group, and R
A compound in which 2tR4 is connected to a polymethylene group having 1 to 5 carbon atoms, and R5 is a polyalkylmethylene group having 1 to 5 carbon atoms.

piperazine, N-methyl-piperazine, N-ethyl-piperazine, 2-methyl-N.

Cyclic compounds such as N'-dimethylpiperazine.

(c) Other compounds 2.5-Dicarboxypiperazine, Siku Lohexane-1,2-diamine-N,N.

N/, N/-tetraacetic acid and salts and tetramethyl ester, ethylenediaminetetraacetic acid and salts and tetramethyl ester, 1,4-azabicyclo[2,2
,2]octane, methyl-substituted 1,4-diazacyclo(2
, 2, 2) Compounds such as octane, adiponitrile, N-methylmorpholine.

(If) Heterocyclic compounds pyridine and alkylpyridines: pyridine, α-hycoline, β-picoline, γ-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2-ethylpyridine
Propylpyridine, 4-propylpyridine, 4-butylpyridine, 4-isobutylpyridine, 4-t-butylpyridine, 2,6-lutidine, 2,4-lutidine, 2.5
-lutidine, 3,4-lutidine, 3,5-lutidine, 2,
4,6-collidine, 2-methyl-4-ethylpyridine,
2-methyl-5-ethylpyridine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methylpyridine, 3,
4-diethylpyridine, 3,5-diethylpyridine, 2-
Methyl-5-butylpyridine, 4-pentylpyridine,
4-(5-nonyl)-pyridine, 2,6-dipropylpyridine, 2-methyl-3-ethyl-6-propylpyridine, 2,6-diethylpyridine, 2,6-dipropylpyridine, 2,6-dipropylpyridine Butylpyridine, 2,6-di-t-butylpyridine; Pyridines containing functional groups: 2-cyanopyridine, 3-cyanopyridine, 4-cyanopyridine, 2,6-dicyanopyridine, 3,5-dicyanopyridine, 2 -cyano-6
-Methyl-pyridine, 3-cyano-5-methyl-pyridine, picolinic acid amide, nicotinic acid amide, isonicotinic acid amide, picolinic acid, nicotinic acid, isonicotinic acid, dipicolinic acid, dipicolinic acid, cinchometronic acid, 5 -butyl-picolinic acid, nicotinic acid alkyl ester, 2-amino-pyridine, 3-aminopyridine, 4-
Aminopyridine, 2,3-diaminopyridine, 2,5-
Diaminopyridine, 2,6-diaminopyridine, 2,3
゜6-triaminopyridine, '2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-5-methylpyridine, 2-amino-6-methylpyridine, 2-amino-4ethylpyridine ,2-amino-4
-propylpyridine, 2-amino-4-(5-nonyl)
-pyridine, 2-amino-4,6-cintylpyridine,
2,6-Diami2-4-methylpyridine, 2,2'-dipyridylamine, 4-(N2H-dimethylamino)pyridine, 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine, 2,6-cyhydroxypyridine , 3-hydroxy-6-methylpyridine, 2-chloropyridine, 2,6-dichloropyridine, 4-chloropyridine, 2-amino-5-chloropyridine, 2-amino-3,5-diaminopyridine N-2 -methylni3,
5-dichloro-6-methylpyridine, 2-amino-5-
Chloro-3-methylpyridine, 2-amino-3,5-dichloro-4-methylpyridine, 2-amino-3,5-dichloro-4,6-cintylpyridine, 4-amino-3,
5-dichloropyridine, pyridine N-oxide, α-picoline-N-oxide, β-picoline-N-oxide,
γ-picoline N-oxide, 2,6-lunasine-N-oxide, 3,5-lutidine-N-oxide, 4-phenylpropylpyridine-N-oxide, 1゜3-di(4
-pyridyl)-propane di-N-oxide, 4-(5-
nonyl)-pyridine-N-oxide, 2-chloropyridine-N-oxide, 4-cyanopyridine-N-oxide, 2-pyridinemethanol, 3-pyridinemethanol 4
-pyridine methanol, 2,6-pyridine methanol,
2-pyridine ethanol, 4-pyridine ethanol, 3
-picolylamine, 4-picolylamine, 2-methylaminoethylpyridine, 4-alkylaminoethylpyridine, 4-piperidinoethylpyridine, 4-(4-pipecolinoethyl)-pyridine, 4-morpholinoethylpyridine; cyclic compound Containing pyridines: 2-phenylpyridine,
4-phenylpyridine, 2-benzylpyridine, 4-benzylpyridine, 4-phenylpropylpyridine, 4,
4'-dipyridyl, 4.4'-dimethyl-2,2'-dipyridyl, 1°3-di(4-pyridyl)propane, 1
, 2-di(4-pyridyl)-ethane, 1,2-di(
4-pyridyl)-ethylene, 1,2,3-tri(4-
pyridyl) propane, 2 t 4 t 6 tri(4-
pyridyl)-s-triazine, 2°4-di(4-pyridyl)-6-methyl-S-triazine, 2,5-di(4
-pyridyl)-8-tetrazine; Alkenylpyridine and high molecular weight pyridines: 2-vinylpyridine, 4-vinylpyridine, 2-vinyl-6-methyl-pyridine, 2-vinyl-5ethylpyridine, 4-
butenylpyridine, 4-vinylpyridine homopolymer,
2-vinylpyridine homopolymer, 2-vinylpyridine copolymer, 4-vinylpyridine-acrylonitrile-
Copolymer 4-vinylpyridine-styrene copolymer, 4-vinylpyridine-divinylbenzene copolymer, 2-vinylpyridine-divinylbenzene copolymer, 4-vinylpyridine homopolymer-N-oxide; Pyrroles: Pyrrolines: Pyrimidines: Pyrazines :
Pyrazole: Pyrazoline: Pyridazine: Imidazole: 1,10-phenanthroline and its derivatives:
1,10-phenanthroline, 4-chloro-1,10-
Phenanthroline, 5-(thiapentyl)-1,1o-
Phenanthroline: Quinoline and its derivatives: Quinoline, 2-(dimethylamino)-6-medoxyquinoline, 8
-Hydroxyquinoline, 2-carboxyquinoline.

Among the above compounds, compounds containing trivalent phosphorus or nitrogen are particularly preferred.

More preferred organic nitrogen group compounds are phosphine compounds containing trivalent phosphorus or heterocyclic compounds typified by pyridine.

The (al) nickel or nickel compound component and (a
2) Halides which are bromides or iodides and (a
3)! Catalysts made of nitrogen or organic nitrogen group compounds containing nitrogen are effective on their own, but their activity is low, and (b) one or more metals selected from lithium, aluminum, and tin are used as cocatalysts. Alternatively, a high reaction rate can be obtained when a compound of the metal is used, or when one or more metals of Group 1 [A of the periodic table or a compound of the metal are used together.

As metals or compounds of these metals used in combination with lithium, aluminum, and tin, magnesium, strontium, barium, and calcium are preferable, and among these, barium is particularly preferable because it also has the advantage of improving the solubility of the catalyst.

Furthermore, when two or more metals or compounds thereof are used, the combination is not limited and can be freely selected, but it is desirable that at least one metal or the compound is selected from the above-mentioned preferred metals.

Furthermore, for example, when barium and tin are used in combination in Example 7, which will be described later, the reaction rate not only increases compared to when barium and tin are used alone, but also the solubility of the catalyst tends to improve.

In this way, lithium, aluminum, tin and Part II
When more than one type of metal or their compound is used in combination, a synergistic effect can be expected (Examples 10-
17).

Cocatalysts can be used in metallic form, for example in the form of finely divided powders, or as various inorganic or organic compounds effective at introducing elements into the reaction system in cationic form under the reaction conditions. can do.

Typical cocatalyst compounds therefore include oxides, hydroxides, halides, preferably bromides and iodides, oxyhalides, hydrides, carbonyls, alkoxides, nitrates, nitrites, phosphates, phosphorous. acid salts, aliphatic,
Salts of cycloaliphatic, naphthenic and aliphatic organic carboxylic acids, such as acetates, butyrates, decanoates, laurates, stearates, benzoates and the like.

Particularly suitable cocatalysts are compounds such as bromides, iodides and organic acid salts, preferably acetates.

The amount of nickel or nickel compound used in the present invention is 1/11 based on the total volume of the reaction solution.
0-6 to 5 mol, preferably 10-4 to 4 mol, more preferably 10-3 to 2 mol, most preferably 5X10
The range from -3 to 1.0 mol is generally selected.

The amount of the halogen compound to be used is 10-3 to 15 mol, preferably 10-2 to 8 mol, more preferably 10-1 to 11, based on the total volume of the reaction solution on a halogen atom basis.
It is used in a range of 4 moles.

The amount of the organic nitrogen compound containing phosphorus or nitrogen is related to the amount of nickel or nickel compound component used, but it is usually 10-1/1 based on the total volume of the reaction solution.
A range of 6 to 10 mol, preferably 10 -4 to 5 mol, more preferably 10 -3 to 2.5 mol is selected.

Similarly, one or more metals or their compounds selected from lithium, aluminum, and tin, which are cocatalysts, or in combination with these and Group 11A, have a ratio of 0.01 to 100 relative to nickel on a metal atom basis. , preferably 0.0
It is used in the range of 3 to 30, more preferably 0.1 to 20, but the amount used is usually 10-6 to 20 mol per 11 per type, based on the total volume of the reaction solution, preferably 10 -4 to 10 mol, more preferably 10-3 to
A range of 5 moles is chosen.

In addition, when using two or more types of promoter metals or compounds of the metals, each may be used within the above range, but
Generally, based on one type of metal atom, the remaining metal atoms are 0
．． 01-100, preferably 0.03-30. More preferably, it is used in a range of 0.1 to 10.

The reaction temperature for carrying out the method of the present invention is, for example, 20 to 350°C, preferably 80 to 300°C, and more preferably 100 to 250°C.

The total reaction pressure may be sufficient to maintain the volatile reaction liquid in a liquid phase and to maintain -carbon oxide at an appropriate partial pressure.

- The preferred partial pressure of carbon oxide is 0.5 to 300 atm, the optimal partial pressure is 1 to 200 atm, and the more optimal partial pressure is 3 to 150 atm.
Although it is atmospheric pressure, a wider partial pressure range of 0.05 to 5000 atmospheres may also be used.

Dimethyl ether, which is a raw material used in the present invention,
Methyl acetate obtained by any method can be used.

For example, dimethyl ether is supplied directly from C05H2 or by dehydration trimerization of methanol, and methyl acetate is usually supplied by esterification of methanol and acetic acid.

In this case, the basic raw material, acetic acid, is produced by the reaction of methanol and carbon monoxide (for example, JP-A-54-59
211, JP-A-54-63002, JP-A-54-666
14) Alternatively, methyl acetate, which is co-produced in the method of converting vinyl acetate to PVA (polyvinyl alcohol), may be used, or methyl acetate produced by the reaction of methanol and synthesis gas [e.g. 51-
149213, JP-A-52-136110. Unexamined Japanese Patent Publication 1972
-136111 etc.] may be used.

It is believed that impurities such as methanol, dimethyl ether, acetic acid, acetaldehyde, dimethyl acecool, halides represented by iodides such as methyl iodide may be mixed into the methyl acetate supplied by the above method. As expected, as long as the overall balance of the reaction is not disturbed, the above-mentioned impurities can be tolerated and the reaction can proceed suitably.

Carbon monoxide used as a raw material gas does not necessarily have to be of high purity; it can be hydrogen, carbon dioxide, methane,
It may contain nitrogen, rare gas, water, etc.

Among them, hydrogen not only does not inhibit the reaction, but also tends to stabilize the catalyst.

In this respect, systems using Group 8 metals other than nickel, such as rhodium or palladium, as catalysts,
- The combined use of carbon oxide and hydrogen produces by-products such as ethylidene diacetate and acetaldehyde, which is undesirable when the intention is to produce acetic anhydride (for example, JP-A-51-1
15409 etc.).

However, in the present invention, which uses nickel or a nickel compound component as a catalyst, the above-mentioned by-products are not generated even if hydrogen is contained in the raw material gas, and it has unique properties different from catalyst systems using rhodium or palladium. have

However, extremely low purity carbon monoxide is not preferable as a raw material gas because it increases the pressure in the reaction system.

Although the presence of water in the reaction raw materials is a common phenomenon, the raw material gas and methyl acetate can tolerate the presence of a small amount of water, which is often present in commercially available reactants, and no problems will occur. .

However, it is generally necessary to avoid the presence of more than 10 moles of water in one or more of the reaction raw materials used in the present invention, as introducing too much water into the reaction system may lead to decomposition of the raw materials and products. easy.

In this respect, it is desirable that the water content be 5 moles φ, more preferably 3 moles or less.

Since water is not a reaction product, maintaining near-anhydrous conditions in the reaction solution is easily achieved by maintaining the necessary reactants introduced into the reaction zone as well as the reaction working fluid in a suitably dry state.

In the method of the present invention, the raw material methyl acetate and/or the reaction product acetic anhydride itself serves as the reaction solvent.
Although it is not necessary to use a solvent, it is also possible to use organic solvents and diluents that are compatible with the raw materials and products in the reaction environment.

Preferred solvents used are substances that participate in the reaction as catalysts, raw materials, reaction intermediates, products or by-products, such as methyl iodide, methyl acetate, acetic anhydride, and acetic acid.

Among these, saturated aliphatic carboxylic acids represented by acetic acid, which is a compound analogous to the target product acetic anhydride, are particularly preferred solvents and act effectively on the reaction of the present invention.

In this regard, it is a preferred practice that 0.1 mol/1 or more, preferably 1 mol/1 or more, more preferably 2 mol/1 or more of a saturated aliphatic carboxylic acid such as acetic acid is present in the reaction solution. It is a mode.

In the present invention, in addition to the above-mentioned solvent, a diluent compatible with the solvent can be used in combination.

Diluents that can generally be used include ethylene glycol diacetate, propylene glycol diacetate, organic acid esters such as dimethyl adipate, methyl benzoate, and dimethyl phthalate, dodecane, hexadecane, benzene, naphthalene, Examples include hydrocarbons such as biphenyl, inorganic acid esters such as triphenyl phosphate, tricresyl phosphate, dibutylphenyl phosphate, tetramethyl orthosilicate, and tetrabutyl silicate.

The method of the invention can be carried out batchwise, semi-batchwise or continuously.

The method of the present invention described in detail above is for producing acetic anhydride by keeping an inexpensive catalyst highly active and reacting methyl acetate or dimethyl ether with carbon monoxide.
It has extremely high industrial significance.

Hereinafter, this will be explained in more detail with reference to Examples.

Example 1 Nickel powder 0.208% as a catalyst. ! F, 2,4-lutidine 0.76&, lithium acetate 1.32.9, methyl iodide 13.9. p, acetic acid as solvent24. O,! 9. 29.6 g of methyl acetate was put into a pressure reactor as a raw material.

After replacing the inside of the system with carbon monoxide, the temperature was raised to 200° C., and the reaction was carried out for 5 hours under the conditions of a total pressure of 80/c4 (hydrogen partial pressure of 10 and a partial pressure of carbon oxide of 50 kg/c).

During this time, as the pressure decreased, carbon monoxide was supplemented.

After cooling, the reaction solution was analyzed and acetic anhydride was detected, accounting for 58% of the feedstock.

Examples 2 to 9 Table 1 shows the results of experiments conducted in a similar manner.

In Example 9, catalysts and solvents other than the raw material dimethyl ether were placed in a pressure-resistant container, and after replacing the system with carbon monoxide,
Dimethyl ether was introduced into the system, and the pressure was increased with carbon monoxide, followed by a reaction.

Examples 10 to 17 Table 2 shows the results of experiments conducted in the same manner as in Example 1.

In addition, in Examples 10 and 13, 25 of the raw material methyl acetate
The time required to convert poly to acetic anhydride was 12 minutes and 11.5 minutes, respectively.

These values are 7, 1 mo it/13-Hr, and 7.5 mol when converted to reactor volume/unit time, respectively.
This corresponds to a reaction rate of /1-Hr.

Further, in all Examples, products derived from the reduction of acetic anhydride such as ethylidene diacetate were not observed.

Furthermore, in Example 17, analysis revealed that the raw material methanol was quantitatively carbonylated and converted to acetic acid.

Claims (1)

[Scope of Claims] 1. Anhydrous by reacting methyl acetate or dimethyl ether with carbon monoxide in the presence of a nickel or nickel compound component, a bromide or iodide halide, and an organic nitrogen group compound containing phosphorus or nitrogen. A method for producing acetic anhydride, the method comprising using one or more metals selected from the group consisting of lithium, aluminum and tin, or a compound of the metals as a co-catalyst. 2. The production method according to claim 1, wherein one or more metals of Group IIA of the periodic table or compounds of these metals are further used as a co-catalyst.