KR920000893B1 - Process for production of carboxylic acid used with ni-sn catalyst - Google Patents

Abstract

A method for recovering carboxylic acid from alkylformate comprises reacting alkylformate with a mixture of Ni (as a main catalyst), Sn (as a cocatalyst), methyl iodide and an organic nitrogen cpd. in a solvent selected from carboxylic acid, carboxylester or a mixture of them, at 10-30 atm. of CO pressure and 140-220 deg.C. Pref. the alkylformate is methyl formate, and the carboxylic acid is acetic acid. The organic nitrogen cpd. is selected from tributylamine, 2-hydroxypyridine or a mixture of them.

Description

Method for preparing carboxylic acid using Ni-Sn catalyst system

The present invention relates to a process for preparing carboxylic acid. More specifically, the present invention relates to a method for preparing carboxylic acid using a nickel (Ni) -tin (Sn) catalyst system.

In particular, the present invention relates to a method for producing monocarboxylic acid, ie, acetic acid, using a Ni-Sn catalyst system.

Acetic acid is one of the important basic chemicals, as well as the acetic acid itself, as a basic raw material for manufacturing chemicals such as acetic acid derivatives, such as acetic anhydride, vinyl acetate, vinyl acetate alcohol, and the like.

Such acetic acid production is usually carried out by carbonylation of methanol and reactions as described in US Pat. Nos. 3,689,533 and 3,7171,670, South African Patent 30/2174 and French Patent 1,573,130. As the catalyst, expensive noble metal catalysts such as rhodium (Rh) are used.

Recently, as another method for preparing acetic acid, a method for preparing carboxylic acid (particularly acetic acid) by isomerization of alkylformate (particularly methylformate) is disclosed in Japanese Patent Nos. 56-83439, 57-212135 and 59-8947. Although they are published in Japanese Patent Application, they also use expensive palladium (Pd) (Japanese Patent 56-83439) and iridium (Ir) (Japanese Patent 57-212135) Rhodium (Rh) (Japanese Patent 59-8947) as reaction catalysts, respectively. I use it.

A method of preparing acetic acid using a low-cost catalyst instead of such a precious metal catalyst has been published. That is, Japanese Patent No. 56-70340 manufactures acetic acid using a nickel catalyst. Catalytic reaction of adding molybdenum or tungsten has been proposed in US Pat. No. 3,839,428, which uses cobalt as an accelerator in nickel catalysts.

In addition, US Pat. No. 2,503,513 uses iron, tungsten, palladium, antimony, etc., which are metals capable of producing carbonyl, as catalysts, but this is not practical because of low reactivity.

Accordingly, an object of the present invention is to provide a method for producing carboxylic acid having improved reactivity while using an inexpensive nickel catalyst system.

Furthermore, another object of the present invention is to provide a method for preparing acetic acid using an inexpensive nickel-tin system as a catalyst.

According to one aspect of the present invention, a solvent selected from the group consisting of a carboxylic acid, a carboxyl ester, and a mixture of an alkylformate as a reactant, nickel as a main catalyst, tin compound as a cocatalyst, an iodine compound and an organic nitrogen group compound And a carbon monoxide pressure of 10-30 atm and a reaction under mixing and stirring at a temperature of 140-220 占 폚.

Furthermore, according to another aspect of the present invention, a mixture of reactant methylformate, main catalyst nickel, cocatalyst tin compound, iodine compound and organonitrogen compound is contacted with acetic acid used as a solvent, and carbon monoxide at 10-30 atmospheres. And a method for producing acetic acid is reacted while mixing and stirring at a temperature of 140-220 ℃.

Hereinafter, the present invention will be described in detail.

The present invention improves the economics of the reaction by using an inexpensive nickel catalyst in place of the expensive noble metal catalyst in isomerization of alkylformates, and overcomes the yield decrease of carboxylic acid due to low reactivity. To this end, in addition to nickel catalysts, additives such as iodine compounds and organonitrogen compounds, and tin are added as promoters for increasing the reactivity.

The method according to the present invention is based on the phenomenon that alkylformates are rapidly carbonylated under low pressure conditions of carbon monoxide in a catalytic reaction system containing a nickel catalyst, an iodine compound, an organic nitrogen group compound, and a tin compound. That is, the present invention is in the presence of an alkyl formate containing carbon monoxide (HCOOR: R is an alkyl group having up to 10 carbon atoms) in the presence of nickel as the main catalyst, an iodine compound as an additive and an organic nitrogen group compound, and a tin compound as a promoter The process of changing to carboxylic acid by easy carbonylation is used, which can be expressed as follows.

Thus, this reaction is essentially a reaction in which a carboxylic acid is produced by a method in which the alkylformate is carbonylated under the pressure of carbon monoxide, but in appearance, the elements constituting the alkylformate are converted to carboxylic acids through rearrangement. It can be said that isomerization reaction.

In carrying out the process according to the invention, the reaction proceeds by mixing and stirring the reactant alkylformate main catalyst, cocatalyst, additives and solvent in a carbon monoxide atmosphere at a suitable pressure until a substantial amount of carboxylic acid is produced.

The reactant alkylformate is methylformate when the resulting carboxylic acid is acetic acid.

Nickel is used as a main catalyst, tin compounds are used as a cocatalyst, and these may use either organic or inorganic compounds.

The tin compound used as the cocatalyst is preferably selected from the group consisting of tetrabutyltin, tetraamyltin and mixtures thereof.

The additives in the present invention serve to stabilize the product by forming ligands, and mixtures of iodine compounds and organonitrogen compounds are used.

As the iodine compound, methyl iodine is preferable, and the organonitrogen compound is generally preferably an amine or a pyridine-based compound containing an alkyl group, and examples thereof include tributylamine, 2-hydroxypyridine, and mixtures thereof.

On the other hand, as a solvent for dissolving solid substances such as a catalyst, it is preferable to use carboxylic acid or carboxyl ester itself which has a high boiling point and which is not used as a reactant under reaction conditions.

It is preferable that the iodine compound and alkylformate added to the reaction maintain a molar ratio of about 0.05: 1-1: 1.

The components of the reaction mixture can be mixed in any order, and the pressure of pure carbon monoxide introduced during the stirring reaction is generally efficient from 10 to 30 atm. The reaction rate is slow at 10 atm or lower and high at at least 30 atm. It is disadvantageous to require a high pressure reactor to maintain the pressure. Subsequently, the temperature is raised while stirring to reach the reaction temperature of 140 ° C. to 220 ° C. at about 1 hour, and a sufficient substantial yield can be obtained within the reaction time of about 1 hour to 4 hours after reaching a constant reaction temperature.

The reaction by the method of the present invention can be separated and purified by a conventional method using a batch reactor or by continuous operation.

For example, when a carboxylic acid is commonly used in a known distillation structure using a higher boiling point than other possible products or reaction residues, volatile components having low boiling point are separated first, and then the remaining carboxylic acid is recovered. can do.

According to the method of the present invention as described above, by using an alkyl formate having an alkyl group having 1 to 10 carbon atoms, carboxylic acids corresponding thereto can be variously produced according to demand.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

50 ml of methyl formate as a main reactant, 50 ml of acetic acid as a solvent, 12 ml of methyl iodine as an iodine compound, 10 ml of tributylamine as an organic nitrogen compound, 0.5 g of nickel powder as a main catalyst and 0.1 ml of tetrabutyl tin as a promoter (0.036 g of tin) ) Was added to a 300 ml volume of a high temperature high pressure stirring reactor (hereinafter referred to as an autoclave reactor), purged five times with carbon monoxide, and loaded with 30 atm of carbon monoxide pressure at room temperature. Subsequently, it heated up at the rate of 2.6 degree-C / min, reached 180 degreeC, and made it react, maintaining this temperature.

One hour after the start of the reaction, the product mixture was collected and analyzed. The conversion rate of methyl formate was 53%, and the selectivity for acetic acid was 92%.

Example 2

The reaction was carried out in the same manner as in Example 1, except that methyl iodine, tributylamine, and tetrabutyl tin were added, and the reaction rate was 33% in methyl formate and 92% in acetic acid in 1 hour. .

[Examples 3 and 4]

The reaction was carried out in the same manner as in Example 1 except that tributylamine and tetrabutyltin were not added (Example 3) and tetrabutyltin was not added (Example 4), and the reaction time was 1 hour. The conversion rate of methyl formate was 33% and 53%, and the selectivity to acetic acid was 94% and 87.5%, respectively.

Example 5-7

The reaction was carried out in the same manner as in Example 1, but the reaction was performed by adding tetrabutyltin as a promoter in the amounts of 0.15 ml (Example 5), 0.5 ml (Example 6) and 0.25 ml (Example 7). In 1 hour, the conversion rates of methyl formate were 93%, 88%, and 93%, respectively, for 54%, 71,%, and 68% acetic acid, respectively.

[Examples 8 and 9]

In the same manner as in Example 1, the pressure of carbon monoxide was reacted at 10 atm (Example 8) and 20 atm (Example 9), respectively, and the conversion rate of methyl formate was 52% in 1 hour, respectively. The selectivity for acetic acid was 63% and 93% and 100%, respectively.

Example 10-14

In the same manner as in Example 1, but the reaction temperature of 140 ℃ (Example 10), 160 ℃ (Example 11), 190 ℃ (Example 12), 200 ℃ (Example 13) and 220 ℃ (Example The reaction was carried out to 14), the conversion rate of methyl formate in the reaction time of 1 hour was found to be 18%, 21%, 68%, 91%, 100%, respectively, in the order of the examples, almost all of the choice for acetic acid % appear.

Example 15

The reaction was carried out in the same manner as in Example 1, except that the tin compound used as a cocatalyst was replaced with 2 ml of tetraamyltin instead of tetrabutyltin. As a result, the conversion rate of methyl formate was 90% and the selectivity to acetic acid in 1 hour. 100% appeared.

Example 16

The reaction was carried out in the same manner as in Example 1 except that the amount of tributylamine, an organic nitrogen compound, was increased to 20 ml and the reaction was performed without adding tetrabutyltin, a tin compound, and the conversion rate of methyl formate was 66% in 1 hour. For 83%, acetic acid was chosen.

Example 17

The reaction was carried out in the same manner as in Example 1, except that the organic nitrogen compound was replaced with 3.99 g of 2-hydroxypyridine instead of tributylamine, and the reaction was performed by adding tetrabutyltin as a promoter in an amount of 0.25 ml. 70% conversion of methylformate and 85% selectivity for acetic acid.

Table 1 below shows the amounts of reactants, reaction conditions, and reaction results for each example in the examples of the present invention.

However, both conversion and selectivity in the table are based on product analysis at 1 hour of reaction time.

On the other hand, Table 2 shows the conversion rate, selectivity, yield, and the like when Mg, Cr, Mo, and the like are used as a cocatalyst for the Ni catalyst in a conventional known method.

TABLE 1

TABLE 2

* Conversion rate, selectivity and yield in the present invention was calculated as follows.

According to the above, the method according to the present invention is not only economical by using a cheap Ni-Sn catalyst without using an expensive noble metal catalyst, but also greatly improves the reactivity of the conventional Ni-based catalyst. You can see.

Claims (7)

In the process for producing carboxylic acid from alkyl formate, a mixture of nickel, cocatalyst tin compound, iodine compound, and organonitrogen compound, which is a main catalyst, together with alkylformate, carboxylic acid, carboxyl ester and mixtures thereof A method for producing a carboxylic acid using a nickel-tin catalyst system, characterized in that the carboxylic acid is recovered by contacting a solvent selected from the group consisting of 10-30 atm and stirring and reacting at 140-220 ° C. . The method of claim 1, wherein the alkyl formate is methyl formate and the carboxylic acid is acetic acid. The method for preparing carboxylic acid using a nickel-tin catalyst system according to claim 1, wherein the initial carbon monoxide has a pressure of 17-23 atm. The method for preparing carboxylic acid using a nickel-tin catalyst system according to claim 1, wherein the iodine compound is methyl iodine. The method of claim 1, wherein the organonitrogen compound is selected from the group consisting of tributylamine, 2-hydroxypyridine, and mixtures thereof. The method of claim 1, wherein the tin compound is selected from the group consisting of tetrabutyltin, tetraamyltin, and mixtures thereof. The method of claim 1, wherein the molar ratio of the iodine compound and the alkyl formate when the reactant is added is 0.05: 1-1: 1.