JPH08198786A - Method for hydrogenating carboxylic acid ester - Google Patents

Abstract

PURPOSE: To hydrogenate a carboxylic acid ester in a suitable manner for industrially and advantageously obtaining an alcohol, especially a higher alcohol in high yield and selectivity by bringing an organic carboxylic acid ester into contact with hydrogen in the liquid phase using a specific catalyst. CONSTITUTION: (A) An organic carboxylic acid ester is brought into contact with (C) hydrogen in the liquid phase in the presence of (B) a cobalt-based catalyst of the formula Co(M)a(Sn)b(Ga)cOx (M is Ru, Rh, Pt or Pd; (a) is 0.01-1; (b) is 0.01-5; (c) is 0.001-1; (x) is a number satisfying the cationic charge of the catalyst) and hydrogenated. Furthermore, the hydrogenating reaction is preferably carried out at 130-350 deg.C reactional temperature under 1-30MPa hydrogen pressure.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing alcohol. Specifically, it relates to a method for producing alcohol by hydrogenation reaction of organic carboxylic acid ester.

[0002]

2. Description of the Related Art Conventionally, a method for hydrogenating a carboxylic acid ester has been known as a method for producing alcohol. For example, as a catalyst to be used for hydrogenating a fatty acid ester, a copper-based catalyst, particularly a copper-chromium-based catalyst, has been industrially praised. However, although the copper-chromium-based catalyst has excellent catalytic performance, it contains harmful chromium, and therefore, it is not safe from the viewpoint of toxicity in the working environment such as waste water during catalyst production or disposal of used catalyst, and safety. There's a problem.

Further, the copper-chromium catalyst is 200 kg /
It is necessary to perform hydrogenation at a temperature of 250 to 350 ° C. under a high pressure of cm ² or more, which is not preferable in terms of plant construction cost and running cost. Further, copper-zinc oxide catalysts, copper-molybdenum oxide catalysts, and copper-based oxide catalysts that do not contain harmful chromium have been proposed as hydrogenation catalysts for carboxylic acid esters. However, the catalyst containing copper as a main component has a problem that copper adheres to the catalyst and the reactor.

Therefore, it has been desired to develop a hydrogenation catalyst other than a copper-based one which does not contain harmful chromium and can be used under mild reaction conditions. For example, use of a Group 8 metal element of the periodic table as a catalyst element other than a copper-based catalyst element is considered. However, the independent system of the Group 8 metal element of the periodic table has almost no hydrogenation ability of carboxylic acid ester in the liquid phase, and the selectivity of the reaction is very poor.

Further, Japanese Patent Publication No. 2-504363,
Japanese Patent Publication No. 3-500657 discloses a method for producing an alcohol by reducing a carboxylic acid ester using a palladium-zinc catalyst, but its reactivity and selectivity are not satisfactory. In particular, it has been difficult to hydrogenate a carboxylic acid ester having a large molecular weight with good selectivity.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an alcohol capable of hydrogenating an organic carboxylic acid ester with good selectivity under mild reaction conditions. Among them, it is an object to provide an industrially advantageous method for producing a higher alcohol by hydrogenating an organic carboxylic acid ester having a large molecular weight with good selectivity.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies on various catalysts capable of hydrogenating a carboxylic acid ester in order to solve the above problems, and as a result, by using the following specific catalysts, The inventors have found that the problems can be solved and have reached the present invention. That is, in the present invention, in the hydrogenation reaction of obtaining an alcohol by contacting an organic carboxylic acid ester with hydrogen in a liquid phase in the presence of a catalyst, a catalyst represented by the general formula [I] is used.

[0008]

Embedded image In the formula, M is a metal component selected from the group consisting of Ru, Rh, Pt, and Pd, a is 0.01 to 1, and b is 0.01 to
5, c represents a number of 0.001 to 1, and x represents a number satisfying the cation charge of the catalyst.) A method for hydrogenating a carboxylic acid ester is provided. To do.

[0009]

SUMMARY OF THE INVENTION Organic Carboxylic Acid Ester The organic carboxylic acid ester used as a raw material for the production of alcohol in the present invention has at least one ester group and is a linear or branched aliphatic, alicyclic or It means an organic carboxylic acid ester having a carboxylic acid moiety having an aromatic hydrocarbon group.

Further, the alcohol part constituting the organic carboxylic acid ester is preferably a lower aliphatic alcohol having 1 to 4 carbon atoms, and particularly preferably methyl alcohol. Specifically, as the aliphatic carboxylic acid ester, coconut oil fatty acid methyl, coconut oil fatty acid ethyl, palm oil fatty acid methyl, methyl stearate, methyl oleate, methyl laurate, methyl instearate, methyl adipate are alicyclic. As the formula carboxylate ester, methyl cyclohexanecarboxylate and methyl 1,4-cyclohexanedicarboxylate are used; as the aromatic carboxylate ester,
Examples include methyl benzoate, dimethyl terephthalate, dimethyl phthalate and the like.

General formula (I) used in hydrogenating a cobalt-based catalyst carboxylic acid ester

[0012]

Embedded image A cobalt-based catalyst represented by CoMaSnbGacOx is used.

M is selected from the noble metal components of the group consisting of Ru, Rh, Pd and Pt. Of these noble metal components, Ru is preferably used. These precious metal components are Co
In the atomic ratio range of 0.01 to 1, preferably 0.
It is selected in the range of 01 to 0.1.

It is considered that Sn greatly contributes to the selectivity of the alcohol of the product, and is used in an atomic ratio of 0.01 to 5, preferably 0.05 to 0.5 with respect to Co. It The Ga component is effective in improving the catalytic activity or shortening the induction period, and has an atomic ratio of 0.001 to Co to Co.
1.0 It is preferably used in the range of 0.01 to 0.5.

Further, x represents the number required to satisfy the cation charge of the catalyst. The raw material compounds for these catalyst components are not particularly limited, and are usually salts of mineral acids such as nitric acid, sulfuric acid and hydrochloric acid; salts of organic acids such as acetic acid; various kinds of hydroxides, oxides, carbonates or complex salts. It is used for the preparation of a catalyst in the form of a compound.

As a method for preparing the catalyst, for example, a coprecipitation method can be adopted. That is, these compounds are mixed in the form of an aqueous solution or suspension of a salt of the metal, a base is added to coprecipitate the metal from the mixture, the precipitate is separated, dried and mixed by firing. The catalyst represented by the above formula (I) can be obtained by converting to an oxide and optionally reducing it to hydrogen for activation.

The preferred salts used for the preparation of the starting aqueous solutions of the metals are nitrates, carbonates, hydrochlorides or acetates. As the base used for precipitation from an aqueous salt solution or suspension, a water-soluble alkali metal or alkaline earth metal hydroxide or carbonate is preferable, and NaOH is particularly preferable because it is inexpensive. The precipitation is a starting aqueous solution of the metal or
It can be completed by adding a base to the mixture of suspensions and adjusting the pH value to at least 10 or more at a temperature of 10 to 90 ° C. The obtained precipitate is separated by filtration, washed with water or the like, and then dried.

Then, it is fired at 400 ° C. to 600 ° C. in air or in an inert atmosphere such as N ₂ . In order to activate the catalyst represented by the formula (I) obtained by calcination, the catalyst is preferably reduced in a H ₂ stream at 200 to 600 ° C. The structure of the catalyst thus obtained has not been clarified at present, but by carrying out the above reduction treatment,
It is presumed that the noble metal component (M), the second metal component (Sn, Ga) and cobalt (Co) are partially or wholly reduced to a metal.

The catalyst can be used by applying a catalytically active substance on an inert carrier, but it is particularly preferable to use the whole catalyst consisting of the catalytically active substance without using a carrier in terms of catalytic activity. Supported catalysts are produced, for example, by precipitating the catalytically active components from their common aqueous solution in the form of hydroxides or carbonates on a support, drying and calcination and activation as described above.

Hydrogenation reaction In the hydrogenation reaction of the organic carboxylic acid ester, the above catalyst is used and the temperature is usually 130 to 350 ° C., preferably 180 to
300 ° C., hydrogen pressure 1-30 MPa, preferably 5-20
It is performed under the condition of MPa. In this case, the reaction system may be either a liquid phase suspension reaction or a fixed bed reaction. Further, the hydrogenation reaction may be carried out without a solvent, or if necessary, a solvent of a kind which does not adversely influence the reaction may be used.

The solvent is not particularly limited, but water; alcohols such as methanol, ethanol, octanol and dodecanol; ethers such as tetrahydrofuran, dioxane and tetraethylene glycol dimethyl ether; hydrocarbons such as hexane, cyclohexane and decalin Is mentioned. In the case of a batch reaction, the amount of catalyst used is 100 parts by weight of the starting organic carboxylic acid ester.
The content is preferably 0.1 to 100 parts by weight with respect to parts by weight, but can be arbitrarily selected within the range where a practical reaction rate can be obtained according to various conditions such as reaction temperature or reaction pressure.

[0022]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. A wax ester is by-produced by transesterification reaction between an alcohol produced in the hydrogenation reaction of an organic carboxylic acid ester and an unreacted carboxylic acid ester. Therefore, the ester conversion rate, alcohol selectivity and wax ester yield described in the examples were defined as follows.

[0023]

[Equation 1]

Catalyst Preparation Example 1 (Production of CoRu _0.05 Sn _0.21 Ga _0.11 Ox Catalyst) 28.6 g of cobalt carbonate and 12 g of gallium nitrate were added to 5 parts.
The mixture was suspended in 00 ml of water and stirred. Separately, 3.75 g of ruthenium chloride trihydrate, 13.0 g of stannous chloride
An aqueous solution of ruthenium and tin was prepared with dihydrate and 50 ml of water, and was slowly added dropwise to the above cobalt and gallium suspension over time. After the dropping, 10 wt% sodium hydroxide aqueous solution was dropped under vigorous stirring to complete the precipitation so that the pH value of the suspension was 12 or more.

The precipitate was filtered and washed several times with water to remove the sodium hydroxide remaining in the precipitate. Then, the precipitate was put into an oven at 100 ° C. and dried. The precipitate was calcined in air at a temperature of 450 ° C. for 3 hours. Then, immediately before being subjected to the reaction, under a H ₂ atmosphere at 300 ° C. for 2 hours.
Time reduction treatment was performed to obtain a reaction catalyst.

Example 1 The catalyst CoRu _0.05 Sn _0.21 Ga prepared according to the above catalyst preparation example 1 was placed in a 200 ml induction-stirring autoclave.
2.5 g of _0.11 Ox and 20 g of methyl laurate were charged under an argon gas atmosphere. Then, nitrogen gas 1M
After replacing the inside of the autoclave with Pa, hydrogen gas of 1 MPa was introduced, and then the temperature was raised to 230 ° C. When the temperature reached 230 ° C., hydrogen gas was injected under pressure into the autoclave so as to have a pressure of 10 MPa, and the reaction was carried out at a constant pressure for 4 hours.

After cooling, the autoclave was opened, the contents were taken out, and the product was quantified by gas chromatography. As a result, the conversion rate of methyl laurate was 93.
%, The lauryl alcohol selectivity was 96%, and the wax ester yield was 9.1%. Immediately after the start of the reaction, no induction period was observed.

Comparative Example 1 CoRu _0.05 Sn _0.21 Ox containing no Ga component was prepared by the same procedure as in Catalyst Preparation Example 1, and the reaction was carried out in the same manner as in Example 1 except that this was used as a catalyst. It was The conversion of methyl laurate was 83%, the selectivity of lauryl alcohol was 100%, and the wax ester yield was 20.4%. In addition, when the catalyst was used, an induction period of 0.4 hours was observed.

Comparative Example 2 CoRu _0.05 Ga _0.20 Ox containing no Sn component was prepared by the same procedure as in Catalyst Preparation Example 1, and the reaction was carried out in the same manner as in Example 1 except that this was used as a catalyst. It was The conversion of methyl laurate was 100%, the selectivity of lauryl alcohol was 0%, and the total amount of conversion was converted to undecane and dodecane.

Comparative Example 3 CoRu _0.05 S in which an Al component is introduced instead of the Ga component.
n _0.21 Al _0.20 was prepared according to the same procedure as in Catalyst Preparation Example 1, and the reaction was carried out in the same manner as in Example 1 except that this was used as a catalyst. Conversion rate of methyl laurate is 73%
The selectivity for lauryl alcohol was 88% and the yield of wax ester was 29.8%. Also, an induction period of 1.2 hours was observed.

Example 2 As a catalyst, CoRu _0.05 Sn _0.20 Ga _0.20 Ox 2.
The reaction was performed in the same manner as in Example 1 except that 5 g was used. The conversion of methyl laurate is 90%, the selectivity of lauryl alcohol is 100%, and the wax ester yield is 13.1.
%Met. The induction period was 0.2 hours.

Example 3 In catalyst preparation example 1, calcination under air at 450 ° C. for 3 hours
Instead of calcination, baking under argon atmosphere at 450 ° C for 3 hours
CoRu is the same as above_0.05Sn _0.21Ga
_0.11Ox was prepared. Example 1 except that this catalyst is used
The reaction was carried out in the same manner. The conversion rate of methyl laurate is
93%, lauryl alcohol selectivity 95%, wack
The yield of sester was 10.2%. Also, during the induction period
I was not able to admit.

Example 4 The same reaction was performed as in Example 1 except that the reaction pressure was changed to 7 MPa. The conversion of methyl laurate is 79
%, The selectivity of lauryl alcohol was 95%, and the yield of wax ester was 26.5%. Moreover, the induction period was not observed.

Example 5 The catalyst Co was placed in a 200 ml induction-stirring autoclave.
Ru_0.05Sn_0.21Ga _0.11Ox 2.5g, 1,4-shi
Dimethyl crohexanedicarboxylate 10.6 g (53.
1 mmol) and 20 g of triglyme were charged and carried out.
By the same operation as in Example 1, hydrogen pressure 10 MPa, reaction temperature 240
The reaction was carried out at ℃ for 4 hours.

As a result, cyclohexanedimethanol was 32.6 mmol, and methyl 4-hydroxymethylcyclohexanecarboxylate and wax ester were 1% each.
4.9 mmol and 2.1 mmol were produced.

[0036]

EFFECTS OF THE INVENTION By using a specific cobalt-based catalyst, a corresponding alcohol can be obtained from an organic carboxylic acid ester in a high yield and a high selectivity by a catalytic hydrogenation reaction.

Claims (3)

[Claims] 1. In a hydrogenation reaction for obtaining an alcohol by contacting an organic carboxylic acid ester with hydrogen in a liquid phase in the presence of a catalyst, a catalyst represented by the general formula [I]: CoMaSnbGacOx ... [I] (Formula 1) Where M is a metal component selected from the group consisting of Ru, Rh, Pt, and Pd, a is 0.01 to 1, and b is 0.01 to
5, c represents a number of 0.001 to 1, and x represents a number satisfying the cation charge of the catalyst. ) A method for hydrogenating a carboxylic acid ester, which comprises using a cobalt-based catalyst represented by the formula (1). 2. The hydrogenation method according to claim 1, wherein M is Ru. 3. The hydrogenation reaction comprises a hydrogen pressure of 1 to 30 MPa,
The hydrogenation method according to claim 1, which is carried out at a reaction temperature of 130 to 350 ° C.