JPH0653703B2 - Carbonylation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses a 0-alkyl and / or 0-aryl compound such as methyl acetate as a raw material to react with carbon monoxide by a catalytic reaction using rhodium as a main catalyst. The present invention relates to a carbonylation method for obtaining a 0-acyl compound such as acetic anhydride.

Acetic anhydride is used in large quantities as a raw material for producing cellulose acetate, and is also useful as a raw material for drugs, fragrances, dyes and the like.

[Conventional technology]

Acetic anhydride is industrially produced by a method of reacting ketene obtained by thermal decomposition of acetic acid with acetic acid.

On the other hand, as part of the so-called Cl chemistry, active research is being conducted to produce acetic anhydride by reacting carbon monoxide with methyl acetate or dimethyl ether. In particular, the method using rhodium as the main catalyst causes the reaction to proceed under milder conditions than other transition element metal catalysts, but the reaction rate is still insufficient for industrial use. Improvements have been made to the catalyst system using various reaction promoters.

For example, an aluminum accelerator is known as a reaction accelerator added to a rhodium-iodine compound (typically methyl iodide) catalyst system (JP-A-60-233030),
There is also known a technique in which a boron compound is further added and used in combination in order to prevent the aluminum accelerator from forming an insoluble precipitate (JP-A-60-199854).

[Problems to be solved by the invention]

However, the catalyst system disclosed in JP-A-60-199854,
That is, when a 0-alkyl and / or 0-aryl compound is carbonylated to produce a 0-acyl compound in the presence of a catalyst system consisting of a rhodium catalyst, an iodine compound, an aluminum promoter and a boron compound, one of the catalyst components is used. It was found that some parts could turn into insoluble precipitates. This causes a substantial decrease in the concentration of the catalyst component in the reaction system, which adversely affects the performance of the carbonylation reaction.
Further, even when the catalyst solution is repeatedly used, which is indispensable for industrial practice, the change in the catalyst composition due to the formation of precipitate is inconvenient.

[Means for solving problems]

The present inventors have conducted extensive studies to overcome the above-mentioned drawbacks of the prior art, and as a result, in the above carbonylation reaction,
Coexistence of a specific catalyst stabilizing component in a catalyst system composed of a rhodium catalyst, an iodine compound, an aluminum promoter and a boron compound significantly suppresses the formation of precipitates of the catalyst component, which is a drawback of the above-mentioned prior art. The present invention has been completed and the present invention has been completed.

That is, in the present invention, a 0-alkyl and / or 0-aryl compound is reacted with carbon monoxide in the presence of a catalyst system consisting of a rhodium catalyst, an iodine compound, an aluminum promoter, and a boron compound to give a 0-acyl compound. In the carbonylation reaction for producing a compound, at least one catalyst stabilizing component selected from (1) lithium, sodium or these compounds, or (2) trivalent nitrogen or trivalent phosphorus compound is present in the reaction system. The present invention relates to a carbonylation method which is characterized in that

Hereinafter, the present invention will be described in detail.

(0-alkyl compound, 0-aryl compound, and 0-
Acyl Compound) The starting material to be carbonylated in the present invention is a 0-alkyl and / or 0-aryl compound capable of producing an alkyl iodide and / or an aryl iodide in the reaction system,
The products are 0-acyl compounds corresponding to 0-alkyl and / or 0-aryl compounds. Typically, production of acetic anhydride by carbonylation of methyl acetate can be mentioned. Also, an ether such as dimethyl ether can be converted to a carboxylic acid anhydride such as acetic anhydride by carbonylation.

Further, as disclosed in JP-A-58-164539, by charging an alcohol or water together with the above-mentioned 0-alkyl and / or 0-aryl compound into the reaction system as a starting material, the carboxylic acid anhydride and the carboxylic acid anhydride are simultaneously obtained. Co-production of carboxylic acids is also possible. For example, methyl acetate and methanol and /
Alternatively, there may be mentioned co-production in which a mixed starting material with water is carbonylated to obtain a mixed product of acetic anhydride and acetic acid.

(Rhodium Catalyst) Rhodium used as the main catalyst in the present invention can be charged into the reaction system as a compound exemplified below. That is, inorganic rhodium salts such as rhodium chloride, rhodium bromide, rhodium iodide and rhodium nitrate, carboxylates such as rhodium acetate, rhodium acetylacetonate, rhodium amine complex salts, and trichlorotrispyridine rhodium, hydridocarbonyltris (triphenyl). Examples include organic rhodium complexes such as phosphine) rhodium, chlorotris (triphenylphosphine) rhodium, and chlorocarbonylbis (triphenylphosphine) rhodium, and cluster complexes such as dodecacarbonyl-tetrarhodium.

The amount of rhodium used is not strictly limited, but the concentration in the reaction solution is 0.1 to 50 mmol / l, preferably 1
It is used in the range of 0 to 30 mmol / l.

(Iodine Compound) The iodine compound used in the present invention is preferably an alkyl iodide and / or aryl iodide conventionally used in this field, but an alkyl iodide and / or aryl iodide can be produced in the reaction system. It may be used in the form of an alkyl iodide and / or aryl iodide precursor. The alkyl iodide and / or aryl iodide precursor is composed of a combination of an iodine component and a 0-alkyl and / or 0-aryl component, and examples thereof include a combination of hydroiodic acid and methyl acetate. Alkyl and / or 0-aryl moieties are used as starting materials in the present invention.
-Alkyl and / or 0-aryl compounds.

Examples of the alkyl iodide and / or aryl iodide include methyl iodide, ethyl iodide, phenyl iodide, and the like. Examples of the iodine component of the alkyl iodide and / or aryl iodide precursors include , Hydroiodic acid, iodine, iodide salts and the like.

The amount of alkyl iodide and / or aryl iodide and / or their precursors used in the reaction solution is not necessarily strictly limited, but is usually 0.5 to 10 mol / l in terms of iodine concentration in the reaction solution, It is preferably used in the range of 1 to 5 mol / l.

(Aluminum accelerator) Examples of the aluminum accelerator used in the present invention include aluminum salts of carboxylic acids such as formic acid, acetic acid, propionic acid, lauric acid and stearic acid, methoxy, ethoxy,
Examples thereof include aluminum alkoxide having an atomic group such as isopropoxy, aluminum halide having an atom such as chlorine, bromine, iodine, aluminum acetylacetonate, aluminum nitrate, and metallic aluminum powder.

The amount of aluminum promoter used is 0.1 to 100 times, preferably 5 to 50 times, the atomic ratio of rhodium. In order to exert a sufficient effect, the concentration of the aluminum promoter in the reaction solution is preferably 0.1 mol / l or more, particularly 0.1 to 0.5 mol / l.

(Boron Compound) As the boron compound used in the present invention, metaboric acid, borohydride (BH ₃ ), sodium borohydride, boron oxide, boric acid, boric acid ester, boron acetate and the like can be used.

The boron compound can be used in an amount of 0.1 to 15 times, preferably 0.4 to 3 times the atomic ratio of the aluminum promoter.

(Catalyst stabilizing component) The catalyst stabilizing component used in the present invention is at least one selected from (1) lithium, sodium or their compounds, or (2) trivalent nitrogen or trivalent phosphorus compound. , (1) include, for example, inorganic salts containing iodide salts such as LiI and NaI, Ac0Li and A
Carboxylates including acetate such as c0Na, hydroxides such as LiOH and NaOH, oxides such as Li ₂ O and Na ₂ O, as well as metals such as Li metal and Na metal, etc. (2) Examples of N (C ₄ H ₉ ) ₃ , N (C ₆ H ₅ ) ₃ , P (C ₄ H ₉ ) ₃ , P (C ₆ H ₅ ) _3, and other amines and phosphines such as N (CH ₃ ) ₄ ] I, [P (C ₆ H ₅ ) ₃ CH ₃ ] I
Onium salts and the like.

In addition, by adding a catalyst stabilizing component, the method disclosed in JP-A-60-199854
Since the aluminum compound solubilizing ability of the boron compound described in JP-A No. 1994-96242 may be slightly reduced, the amount of the catalyst stabilizing component used is within a range that does not impair the aluminum compound solubilizing ability of the boron compound. It is important to use. The atomic ratios of the aluminum promoter, the boron compound and the catalyst stabilizing component which are usually used are a,
If b and c, then the formula (1) The catalyst stabilizing component is used when the value of x represented by is 0 or more, preferably 0.1 or more.

Reaction Conditions The carbonylation reaction in the present invention can be carried out in the presence of hydrogen and often gives desirable results. The amount of hydrogen used is preferably added in a concentration range of 1 to 30% in a mixed state with carbon monoxide. It can be used at a high concentration of 30% or more, but it increases the amount of ethylidene diacetate and methane by-products. Particularly, a hydrogen concentration range of 5 to 20% is desirable from the viewpoint of carbonylation reaction rate and by-products.

The reaction temperature and pressure for carrying out the present invention can be appropriately determined with reference to the prior art. The reaction temperature is usually 130 ~ 250 ℃, preferably used 150 ~ 200 ℃,
The pressure of carbon monoxide used in the reaction is 1 to 100 kg / cm ² G, preferably 5 to 100 kg / cm ² G, and particularly 20 to 80 kg / cm ² G.

〔The invention's effect〕

Carbonylation to produce a 0-acyl compound by reacting a 0-alkyl and / or 0-aryl compound with carbon monoxide in the presence of a catalyst system consisting of a rhodium catalyst, an iodine compound, an aluminum promoter and a boron compound. In the reaction, at least one catalyst stabilizing component selected from (1) lithium, sodium or a compound thereof, or (2) trivalent nitrogen or a trivalent phosphorus compound is present in the reaction system. According to the carbonylation method of the present invention, it is possible to significantly suppress the precipitation of the catalyst component, which is particularly observed in the separation process of distilling and separating the catalyst and the product.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Comparative Example 1 In order to show that the catalyst system containing no catalyst stabilizing component has low thermal stability under carbon monoxide deficiency, a catalyst system consisting only of a rhodium catalyst, an iodine compound, an aluminum promoter and a boron compound is described below. An experiment was conducted.

The following reagents were placed in a Hastelloy B stirred autoclave with an internal volume of 350 ml.

After replacing the internal air with carbon monoxide,
It was press-fitted to 15 kg / cm ² G, and further 5 kg / cm ² of hydrogen was added to make a total of 20 kg / cm ² G. Then, the mixture was heated and stirred at 170 ° C. for 2 hours. Then, the autoclave was cooled to room temperature, the residual pressure was released to normal pressure, and 44.0 g of an additional liquid having the following composition was added.

Next, after replacing the residual gas (mainly carbon monoxide and hydrogen) inside the autoclave with nitrogen gas, nitrogen is replaced with 5 kg / cm ²
Pressed until it reached G. Furthermore, the solution in the autoclave was homogenized by stirring at room temperature for 10 minutes. The catalyst liquid thus obtained corresponds to the catalyst liquid obtained in the process of distilling and separating the carbonylation reaction liquid into a product and a catalyst liquid.

First, in order to know the composition of the catalyst solution in the autoclave before heating in the absence of carbon monoxide, a part of the catalyst solution in the autoclave was extracted and analyzed. The analysis value is first
It is shown in the column "Before heating" in the table.

Next, the autoclave was heated and stirred at 150 ° C. for 90 minutes. Then, the autoclave was cooled to room temperature, released after releasing the pressure, and 1.0 g of a black precipitate was deposited in the catalyst solution. The supernatant of the catalyst solution was analyzed, and the analysis values are shown in the column "after heating" in Table 1.

As shown in Table 1, the concentration of dissolved rhodium was reduced to about 52% before heating by heating. This result shows that the catalyst solution containing no catalyst stabilizing component is thermally stable under carbon monoxide deficiency. Is extremely low.

Example 1 Lithium iodide (LiI) which is a catalyst stabilizing component together with RhI ₃
The same experiment as in Comparative Example 1 was conducted except that 4.34 g of was added.

The catalyst solution after heating was uniform and had no sediment.

The composition of the catalyst solution before and after heating is shown in Table 2.

Example 2 Sodium iodide (Na) which is a catalyst stabilizing component together with RhI ₃
The same experiment as in Comparative Example 1 was conducted except that 4.86 g of I) was added.

The catalyst solution after heating was uniform and had no sediment.

The composition of the catalyst liquid before and after heating is shown in Table 3.

Tetramethylammonium Yoji de with Example 3 RhI ₃ ([N
The same experiment as in Comparative Example 1 was conducted except that 3.26 g of (H ₃ ) ₄ ] I) was added.

The catalyst solution after heating was uniform and had no sediment.

The composition of the catalyst liquid before and after heating is shown in Table 4.

Except that the triphenylmethyl phosphonium Yoji de with Example 4 RhI _{3 ([P (C 6 H 5) 3} CH 3 ] I) was added 7.86g were the same experiment as in Comparative Example 1.

The catalyst solution after heating was uniform and had no sediment.

Table 5 shows the composition of the catalyst liquid before and after heating.

The results of Examples 1 to 4 above show that the catalyst system containing the catalyst stabilizing component has significantly higher thermal stability under carbon monoxide depletion than the catalyst system containing no catalyst stabilizing component. There is.

The following experiments were performed to show that the present invention is also effective in a continuous carbonylation process involving the recycling and reuse of catalysts commonly used in industrial carbonylation processes.

Comparative Example 2 The carbonylation reaction involving the recycling and reuse of the catalyst was carried out using the experimental apparatus schematically shown in FIG. Carbon monoxide, hydrogen and
A mixed solution of 52.7 wt% methyl acetate and 47.3 wt% methanol was continuously supplied to the reactor 1 through the channels 6, 7 and 8, respectively. The liquid volume in the reactor was kept at 1 by continuously withdrawing a part of the reaction liquid through the flow path 10 by the valve 5. The pressure inside the reactor was maintained at 28 kg / cm ² G by continuously withdrawing a part of the reaction gas through the channel 9 by the valve 4. The temperature inside the reactor was kept at 185 ° C by adjusting the heating amount of the reactor. The composition of the reaction solution was kept at the composition shown in Table 6.

The ratio of carbon monoxide to hydrogen in the reaction gas extracted from the valve 4 was kept as follows.

Carbon monoxide / hydrogen = 85/15 (volume ratio) The reaction liquid extracted by the valve 5 is introduced into the evaporation tank 2 which is a high temperature atmosphere depleted of carbon monoxide, and is a catalyst liquid mainly containing rhodium, aluminum and boron. And a distillate mainly consisting of methyl iodide, methyl acetate, acetic acid and acetic anhydride. The catalyst solution was recirculated to the reactor 1 after joining the catalyst replenishing flow path 13 for maintaining the catalyst concentration in the reaction solution through the flow path 12. On the other hand, the distillate is introduced into the distillation column 3 through the flow path 11 and separated into a distillation column distillate mainly composed of methyl iodide and methyl acetate and a distillation column distillate mainly composed of acetic acid and acetic anhydride. Was done. The distillation column distillate is joined through a flow path 15 with a methyl iodide replenishment flow path 14 for maintaining the methyl iodide concentration in the reaction solution, and then the reactor 1
Was recirculated to. On the other hand, the distillation column eluate was extracted as a crude product of the carbonylation product through the channel 16.

After continuous operation for 88 hours, 301 g of acetic acid and 245 g of acetic anhydride were obtained through the channel 16 every hour.

When the apparatus was inspected after the continuous operation, a total of 16.0 g of black solid matter was found inside the evaporation can 2 and in the catalyst liquid circulation passage 12, and no solid matter was found at other parts. The analytical values of the black solid matter are shown in Table 7.

The result is a rhodium catalyst that contains no catalyst stabilizing component,
A catalyst system consisting only of an iodine compound, an aluminum promoter and a boron compound has been shown to be extremely unstable even in a continuous carbonylation process involving cyclic reuse of the catalyst.

Example 5 The same experiment as in Comparative Example 2 was carried out except that sodium iodide was added to the catalyst solution to keep the sodium concentration in the reaction solution at 2950 ppm.

After continuous operation for 88 hours, acetic acid and acetic anhydride similar to those in Comparative Example 2 were obtained through the channel 16.

When the apparatus was inspected after the operation was completed, a total of 0.1 g of black solid matter was found inside the evaporation can 2 and in the catalyst liquid circulation passage 12, but no solid matter was found in other parts. The analytical values of the black solid matter are shown in Table 8.

Comparing the results of Table 8 with the results of Comparative Example 2, by adding sodium as a stabilizing component, the precipitation amounts of rhodium, aluminum and boron were each 1/10.
It is very small, 0, 1/282 and 1/107. This result shows that in the continuous carbonylation method involving the recycling and reuse of the catalyst, the catalyst system containing the catalyst stabilizing component is much more stable than the catalyst system containing no catalyst stabilizing component.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an experimental apparatus used in the continuous carbonylation method of Comparative Example 2 and Example 5. 1 ... Reactor, 2 ... Evaporating can 3 ... Distillation column, 4,5 ... Valve 6 ... Carbon monoxide flow path, 7 ... Hydrogen flow path 8 ... Methyl acetate and methanol mixed solution flow path 9 ... Reactant gas channel, 10 ... Reactant channel 11 ... Distillate channel, 12 ... Catalyst fluid channel 13 ... Catalyst replenishment channel 14 ... Methyl iodide replenishment channel 15 ... Distillation tower distillate flow path 16 ...... Distillation tower distillate flow path

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Claims (1)

[Claims] 1. A catalyst system comprising a rhodium catalyst, an iodine compound, an aluminum promoter, and a boron compound,
In a carbonylation reaction for producing acetic anhydride by reacting methyl acetate or dimethyl ether with carbon monoxide, (1) lithium, sodium or their compounds, or (2) trivalent nitrogen or trivalent phosphorus compounds A carbonylation method characterized in that at least one selected catalyst stabilizing component is allowed to coexist in a reaction system.