JPH0940609A - Method for producing methyl formate - Google Patents

Abstract

(57) Abstract: Methyl formate is industrially advantageously produced from methanol and carbon monoxide. [Structure] Methanol is reacted with carbon monoxide in the presence of a strongly basic anion exchange resin catalyst having an anion exchange group consisting of a quaternary ammonium group having a trialkyl-substituted nitrogen atom introduced therein.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing methyl formate from methanol and carbon monoxide.
Methyl formate is one of industrially important organic chemicals used as formic acid, formamide, various carboxylic acid esters, raw materials for synthesizing organic compounds, solvents and the like.

[0002]

Methyl formate is produced by esterification of formic acid and methanol, decomposition of methyl nitrite, dimerization of formaldehyde, oxidation of methanol, direct synthesis from hydrogen and carbon monoxide, and carbon monoxide of methanol. Methods such as carbonylation with methanol and dehydrogenation of methanol are known. Among them, the methods industrially put to practical use are the carbonylation method of methanol and the dehydrogenation method of methanol which have been practiced for a long time.

The methanol dehydrogenation method is a new method that has recently been put into practical use, and it has been put into practical use by developing a new highly selective catalyst.
And JP-A-58-163444. The carbonylation method of methanol has been practiced in Europe and the United States for a long time, and is still known as the main production method of methyl formate. Known catalysts used in this reaction include metal alkoxides, strong base catalysts such as DBU (diazabicycloundecene), and transition metal carbonyls.

As an example of the metal alkoxide catalyst, an alkali metal alkoxide is used, and the temperature is 60 to 130 ° C.
It is known to react at a pressure of 40 to 200 atm [Kokaika, Vol. 59, pp. 871-875 (1956)]. In the metal alkoxide catalyst, hydrogen may coexist in carbon monoxide gas, but the water and carbon dioxide in the raw material methanol and carbon monoxide become catalyst poisons, and the catalyst is deactivated and consumes water and carbon dioxide. It is necessary to reduce carbon as much as possible,
The purification system is an important step. The method using a metal alkoxide is a method that is actually industrially performed because of high methyl formate selectivity, but many proposals including a reaction method, a reactor shape, a process, etc. have been made in order to proceed more favorably. .

Nikkan 1 for strong base catalysts such as DBU
977, No. 4, pp. 457-465, using methyl cellosolve solvent with DBU as catalyst, pressure 170-400 atm, temperature 4
Experiments are conducted at 5-200 ° C. For metal carbonyl catalysts, see Journal of Molecular Catalysis 45 (198).
8), pp. 235-246, states that ruthenium hydridocarbonium catalysts are effective for the synthesis of formate esters by the carbonylation of alcohols. This catalyst is effective for primary alcohols, but not for secondary and tertiary alcohols.

Although all of the above-mentioned examples are reactions in a homogeneous catalyst system, there is an example in which an ion exchange resin catalyst is used as an example of a heterogeneous catalyst system. U.S. Pat. No. 4,100,3
No. 60 uses a strong basic anion exchange resin to give 0-2.
00 ° C., 100-5,000 psi. It provides a method of reacting under the conditions of. However, the flow reaction by this method has a low reaction rate and is not practical.

[0007]

The reaction with the above homogeneous catalyst has the advantage that the catalyst concentration in the solution is uniform and the reaction occurs uniformly. However, it is difficult to separate the reaction solution, methyl formate and unreacted methanol, from the catalyst solution from the catalyst solution. In many cases, a method such as distillation is generally used to separate the mixed solution containing them and the catalyst solution, but a large amount of heat energy is required, and some catalysts change due to heating such as distillation. However, there is a problem that it may be altered. Further, in the reaction with a homogeneous catalyst, it is easily affected by impurities in the raw material methanol and the raw material carbon monoxide gas, and in particular, water and carbon dioxide react with the catalyst to change into an insoluble substance and become inseparable, Alternatively, formic acid is produced as a by-product, and not only the catalyst loss but also the operation itself cannot be performed. In order to eliminate this effect, it is necessary to thoroughly purify the raw material methanol and the raw material carbon monoxide, but it requires complicated steps and a large amount of energy, which is an obstacle to industrialization. US Patent 4,10
No. 0,360 proposes a method for producing methyl formate from methanol and carbon monoxide using an ion exchange resin as a catalyst. According to this, the anion exchange resin is poly (styrenedivinylbenzene), and R is an alkyl group having 1 to 4 carbon atoms or an OH-substituted alkyl group having 1 to 2 carbon atoms.
It is a resin having an exchange group of R ₃ . However,
According to this method, although the reaction pressure is high, the reaction results are low and it cannot be said that this method is sufficient.

[0008]

As described above, the reaction with a homogeneous catalyst complicates the process and requires a large amount of energy. Under such circumstances, the inventors thought that a heterogeneous catalyst, which is easy to separate from the catalyst and is advantageous in terms of thermal energy, is industrially more suitable. The inventors have found that methyl formate can be industrially advantageously obtained under mild reaction conditions by using a strongly basic anion exchange resin having a substituted nitrogen atom introduced, and have reached the present invention. That is, the present invention is characterized by reacting methanol and carbon monoxide in the presence of a strongly basic anion exchange resin catalyst having an anion exchange group consisting of a quaternary ammonium group having a trialkyl-substituted nitrogen atom introduced. And a method for producing methyl formate.

The raw material methanol in the present invention can be used as it is as an industrial grade. However, it is preferable to minimize the water content in methanol by using a desiccant prior to use. Although carbon monoxide as a raw material may contain, as other gas, an inert gas such as hydrogen and nitrogen in the main reaction, but if the carbon monoxide concentration is too low, the carbon monoxide content during the reaction may be reduced. Since it is necessary to increase the total pressure to maintain the pressure, the carbon monoxide concentration in the raw material gas is preferably 20% or more. Since carbon dioxide and water adversely affect the reaction, it is preferable to use the raw material carbon monoxide after it has been subjected to a gas purification process such as dehumidification and decarbonation.

In the reaction of the present invention, the molar ratio of methanol to carbon monoxide is theoretically 1: 1; however, it is advantageous under the condition of excess carbon monoxide, and the molar ratio is 1: 1 to 100.
It is. Considering the recycling and reuse of unreacted carbon monoxide, the molar ratio is preferably 1: 1.2 to 50. Unreacted carbon monoxide separated from the reactor or reaction tube can be circulated to the reaction system. The reaction temperature of methanol and carbon monoxide is 0 to 150 ° C., and is limited by the heat resistant temperature of the ion exchange resin itself, so a range of up to 100 ° C. is usually selected. The reaction pressure is 5 to ²⁰⁰ kg / cm ² , preferably 10 to 100 kg / cm ² .

In the present invention, the method of reacting methanol with carbon monoxide is not particularly limited, and a tank type reactor having an internal stirrer is used in a batch system while feeding carbon monoxide or methanol as a raw material. Any of the semi-batch methods can be used. A tubular reactor is filled with an ion-exchange resin catalyst, and a trickle bed system in which carbon monoxide and methanol are continuously supplied from the upper part of the reaction tube in parallel flow, and methanol is continuously supplied from the lower part of the reaction tube in parallel or countercurrent A method of continuously supplying carbon, a method of circulating a part of the reaction solution at the exit of the reaction tube in a tubular reaction tube and supplying it with newly supplied methanol, or the like can be implemented. By these methods, a mixture of methanol and methyl formate separated from the catalyst can be obtained from the reactor or reaction tube, and methyl formate can be separated by distillation, and then the recovered methanol can be circulated as a reaction raw material.

Generally, there are many kinds of ion exchange resins. The strongly basic quaternary type includes type I and type II, which differ depending on the type of functional group. Type I has four methyl groups coordinated to the nitrogen atom, and type II has one of the four substituted with an ethanol group.
They dissociate in both acidic and alkaline solutions and have an ion exchange capacity. In the present invention, a type I strong basic ion exchange resin is used.

The ion-exchange resin according to the present invention is a strong base anion-exchange resin having an anion-exchange group introduced with a trialkyl-substituted nitrogen atom among quaternary ammonium groups, which corresponds to Bayer's Levatit M504,
Levacit AP247, Levatit MP500, Mitsubishi Chemical Diaion SA11A, Organo Organo XT
5021 and the like. Since this ion exchange resin usually exists in a state of being neutralized with chlorine (chlorine type), it is used after being subjected to a regeneration treatment with an aqueous alkali hydroxide solution in order to express the basicity of the OH type. This reaction is an equilibrium reaction, and the methyl formate that is produced has a lower boiling point than the raw material methanol.Therefore, adopt the reactive distillation in which the produced methyl formate is continuously extracted by distillation outside the system while disrupting the equilibrium. You can also If this method is adopted, methyl formate can be easily obtained with a high reaction rate.

[0014]

The present invention will be described more specifically with reference to the following examples. However, the present invention is limited to these examples.

Examples 1 to 8 A predetermined amount of ion exchange resin and methanol (manufactured by Mitsubishi Gas Chemical Co., Ltd.
Molecular sieve dried). The lid of the autoclave was closed, the inside was sufficiently replaced with nitrogen gas, and it was confirmed that there was no leakage. Then, the autoclave was filled with carbon monoxide to a predetermined pressure. This was placed on a shaking table that can be heated from the outside, and heated to a predetermined temperature while shaking. After reacting with shaking for 2 hours, the autoclave was removed from the shaking table, immersed in water and cooled. The internal gas was gradually purged by opening the autoclave valve, the gas amount was measured, and the composition was analyzed.
When the autoclave pressure became the same as the atmospheric pressure, the lid was opened and the contents were taken out, weighed and analyzed. Table 1 shows the reaction conditions and the results. As a result of analysis by a gas chromatograph, in each example, only methanol as a raw material and methyl formate as a product were not detected. The ion-exchange resins used were Revert M504 manufactured by Bayer in Examples 1 to 5, Revatit AP247 manufactured in Example 6, DIAION SA11A manufactured by Mitsubishi Chemical in Example 7, and Organo XT5021 manufactured by Organo in Example 8.

[0016]

[Table 1] Example 1 2 3 4 5 6 7 8 Resin amount (g) 0.56 0.56 0.56 1.12 0.56 0.57 0.65 0.51 Methanol charge amount (mmol) 340 350 344 383 342 361 357 331 CO filling pressure (kg / cm ² G ) 90 50 20 50 50 50 50 50 Reaction temperature (℃) 60 60 60 60 40 60 60 60 Methyl formate yield (mol%) 56.6 24.9 9.2 32.3 6.9 16.8 17.9 15.3

Examples 9 to 11 A predetermined amount of ion exchange resin (Bayer's Levatit M504) was placed in a stainless steel autoclave having an internal volume of 100 ml.
And methanol. The lid of the autoclave was closed, the inside was sufficiently replaced with nitrogen gas, and it was confirmed that there was no leakage. Next, the autoclave was filled with a mixed gas having a different ratio of carbon monoxide and hydrogen up to a predetermined pressure.
Thereafter, the same procedure as in Examples 1 to 8 was performed. Table 2 shows the reaction conditions and the results. As a result of analysis by a gas chromatograph, in each example, only methanol as a raw material and methyl formate as a product were not detected.

[0018]

[Table 2] Example 9 10 11 Resin amount (g) 0.56 0.565 0.56 Methanol charge amount (mmol) 347 342 326 Mixed gas filling CO: H ₂ 50:50 70:30 30:70 Pressure (kg / cm ² G) 100 70 67 Reaction temperature (℃) 60 60 60 Methyl formate Yield (mol%) 30.5 29.0 7.6

Examples 12 to 13 A stainless steel tank type autoclave having an internal volume of 100 ml and having an internal stirrer was charged with a predetermined amount of ion exchange resin (Levacit M504 manufactured by Bayer) and methanol.
The lid of the autoclave was closed, the inside was thoroughly replaced with nitrogen gas, and it was confirmed that there was no leakage. Then, the autoclave was filled with carbon monoxide to a predetermined pressure. This was placed in an electric furnace and heated to a temperature of 60 ° C while stirring the inside. As the reaction progresses, carbon monoxide is consumed and the pressure drops, so the reaction pressure from another carbon monoxide accumulator
After reacting for a predetermined time while supplying 50 Kg / cm ² G, the autoclave was immersed in water and cooled. The internal gas was gradually purged by opening the autoclave valve, the gas amount was measured, and the composition was analyzed. When the autoclave pressure became the same as the atmospheric pressure, the lid was opened and the contents were taken out, weighed and analyzed. Table 3 shows the reaction conditions and results. As a result of analysis by a gas chromatograph, in each example, only methanol as a raw material and methyl formate as a product were not detected.

[0020]

[Table 3] Example 12 13 Amount of methanol charged (mol) 1.56 1.56 Reaction time (hr) 8 5.5 Stirring speed (rpm) 150 1200 Methyl formate yield (mol%) 31.5 76.9

Example 14 13 ml of an ion exchange resin (Rebatit MP500 manufactured by Bayer) was placed in a stainless steel reaction tube having an inner diameter of 13φ and a length of 300 mm.
Was charged, and methanol and carbon monoxide were supplied from the upper portion in a downward cocurrent manner to cause a reaction. Reaction pressure 20Kg / cm
² G, reaction temperature 40 ° C., methanol LHSV 0.17 /
The methyl formate yield was 80 mol% under the conditions of hr and CO flow rate of the reaction tube outlet of 22 ml / hr. As a result of analysis by gas chromatography, only methanol as a raw material and methyl formate as a product were not detected.

Comparative Examples 1 and 2 A stainless steel autoclave having an internal volume of 100 ml was filled with the above-mentioned type II strong basic ion exchange resin and methanol. The lid of the autoclave was closed, the inside was sufficiently replaced with nitrogen gas, and it was confirmed that there was no leakage. Then, the autoclave was filled with carbon monoxide to a predetermined pressure. This was placed on a shaking table that can be heated from the outside, and heated to a predetermined temperature while shaking. After the shaking reaction for a predetermined time, the autoclave was removed from the shaking table, immersed in water and cooled. The internal gas was gradually purged by opening the autoclave valve, the gas amount was measured, and the composition was analyzed.
When the autoclave pressure became the same as the atmospheric pressure, the lid was opened and the contents were taken out, weighed and analyzed. The reaction conditions and results are shown in Table 4. The ion exchange resin used in Comparative Example 1 was Revat MP600 manufactured by Bayer, and Comparative Example 2 was used.
Then, it is Organo Amberlite IRA-910.

[0023]

[Table 4] Comparative Example 1 2 Charge amount of methanol (mmol) 344 358 CO filling pressure (kg / cm ² G) 50 50 Reaction temperature (° C) 40 40 Methyl formate yield (mol%) 3.7 2.2

[0024]

As is clear from the above examples, a strongly basic anion exchange resin having an anion exchange group consisting of a quaternary ammonium group having a trialkyl-substituted nitrogen atom introduced by the method of the present invention. By reacting methanol and carbon monoxide in the presence of a catalyst, a pressure of generally 10
Methyl formate can be obtained in a high yield under extremely mild reaction conditions of 0 kg / cm ² G or less and a reaction temperature of 40 to 60 ° C. In the method of the present invention, since the reaction is carried out at a low temperature, the selectivity of methyl formate is extremely high, and since it is a reaction using a heterogeneous catalyst, it is easy to separate it from the catalyst and it is a process that is also advantageous in terms of thermal energy. . Therefore, methyl formate can be industrially advantageously produced by the method of the present invention, and the industrial significance of the present invention is extremely great.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Okamoto 182 Tayuhama, Niigata City, Niigata Prefecture Mitsubishi Gas Chemicals Co., Ltd., Niigata Research Laboratory (72) Inventor Kenji Nakamura 182 Tayuhama, Niigata City, Niigata Mitsubishi Gas Engineering Niigata Research Institute Co., Ltd.

Claims (1)

[Claims] 1. A method of reacting methanol with carbon monoxide in the presence of a strongly basic anion exchange resin catalyst having an anion exchange group composed of a quaternary ammonium group having a trialkyl-substituted nitrogen atom introduced therein. And a method for producing methyl formate.