JP4826709B2 - Method for producing purified alcohol - Google Patents

Description

  The present invention relates to a process for producing an alcohol by producing a condensate by condensation and dehydration reaction of an aldehyde and hydrogenating it, and more specifically, by a condensation and dehydration reaction of normal butyraldehyde (NBD). -It relates to a method for producing 2-ethylhexanol (2EH) by producing ethylhexenal (EPA) and hydrogenating it.

  The production of 2-ethylhexanol (2EH) from normal butyraldehyde (NBD) has been carried out industrially on a large scale. This process includes an NBD condensation step to obtain 2-ethylhexenal (ethylpropylacrolein, EPA) by aldol condensation and dehydration of NBD2 molecules, an EPA hydrogenation step in which the obtained EPA is reacted with hydrogen to obtain crude 2EH, and It consists of a 2EH purification step that purifies crude 2EH to the desired purity to obtain a 2EH product. The crude 2EH is purified mainly by distillation.

Alcohols such as 2EH as industrial products traded on the market are required to have high purity, but are also required to be less colored in the sulfuric acid coloring test.
Conventionally, aldehydes such as 2-ethylhexanal (2HA) and unsaturated alcohols such as 2-ethylhexenol are known as substances that deteriorate the results of the 2EH sulfuric acid coloring test. For example, Patent Document 1 discloses a catalyst precursor containing a component represented by the following general formula (i) as a hydrogenation catalyst in a method for producing a corresponding saturated alcohol by reacting aldehyde with hydrogen in a gas phase. A method for reducing unsaturated alcohol in 2EH by using a reduced product of the composition is disclosed.

(In the formula, X represents a transition metal of Group 8 or Group 4A of the periodic table, a to f represent the contents when each component is converted to an oxide, a is 20 to 50% by weight, b Is 0 to 50 wt%, c is 0 to 50 wt%, d is 0.1 to 5.0 wt%, e is 0.1 to 5.0 wt%, and f is 0.01 to 3.0 wt% Is shown.)
However, even in 2EH from which aldehydes and unsaturated alcohols have been removed, the sulfuric acid coloring test results may be poor. Accordingly, the present invention is intended to provide a method for producing purified alcohol (particularly 2EH) that achieves good results in the sulfuric acid coloring test.
JP-A-8-3084

  According to the study by the present inventors, when a compound having a carbon-carbon double bond in a hetero ring such as a pyran ring or a dihydropyran ring is present in the alcohol, the result of the sulfuric acid coloring test of the alcohol Getting worse. Although these compounds and alcohols can be separated slightly by distillation, they are extremely difficult to separate by ordinary distillation, and the abundance of these compounds in the crude alcohol subjected to the purification treatment may be reduced. is important. In order to obtain an alcohol that exhibits good results in the sulfuric acid coloring test as a product, it is desirable that the concentration of these compounds in the crude alcohol be 200 wtppm or less, particularly 100 wtppm or less. According to the study by the present inventors, one of the methods for reducing the abundance of these compounds in the crude alcohol is to distill the reaction product obtained by condensation / dehydration of aldehyde to distill the condensate. The high boiling point substances are separated by obtaining the product and supplied to the hydrogenation step. Further, even if the hydrogenation of the condensate is carried out in two stages of catalytic hydrogenation and catalytic hydrogenation using a different catalyst, the abundance of these compounds in the crude alcohol can be reduced.

The present invention has been achieved based on such findings, and the gist of the present invention resides in the following (1) to (8).
(1) a condensation step in which an aldehyde is subjected to aldol condensation and dehydration to give a corresponding condensate,
A carbon-carbon double bond in a ring in a method for producing an alcohol comprising a hydrogenation step of hydrogenating the condensate to form a crude alcohol, and a purification step of distilling the crude alcohol to obtain a purified alcohol. A method for producing a purified alcohol, comprising supplying a crude alcohol having a concentration of a compound having an oxygen-containing heterocycle having 200 wtppm or less to a purification step.

(2) The production method according to (1), wherein the aldehyde is normal butyraldehyde, the condensate is 2-ethylhexenal, and the alcohol is 2-ethylhexanol.
(3) In the above (1) or (2), crude alcohol having a concentration of a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring is 100 wtppm or less is supplied to the purification step. The manufacturing method as described.

(4) Any of (1) to (3) above, wherein the compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring is a compound having a pyran ring or a dihydropyran ring The manufacturing method as described in.
(5) The production method according to any one of (1) to (4) above, wherein the content of the high boiling point product is reduced from the condensate obtained in the condensation step and then supplied to the hydrogenation step.

(6) The method according to any one of (1) to (5) above, wherein the hydrogenation step is performed using at least two types of catalysts.
(7) In any one of the above (1) to (5), the hydrogenation step is performed in two stages, a gas phase hydrogenation step and a liquid phase hydrogenation step using a different catalyst. The manufacturing method as described.
(8) The production method according to any one of (1) to (7) above, wherein the sulfuric acid color test of the purified alcohol obtained by the purification step is 30 APHA or less.

  According to the present invention, it is possible to produce a purified alcohol having a good result of the sulfuric acid coloring test.

  In the present invention, first, an aldehyde is subjected to aldol condensation and dehydration to obtain a condensate. The aldehyde is not particularly limited, and a saturated aldehyde having at least 3 carbon atoms and usually having 3 to 10 carbon atoms is used. Saturated aldehydes include linear and side chain aldehydes, specifically, propionaldehyde, butyraldehyde, valeraldehyde, heptylaldehyde, nonylaldehyde and the like, preferably butyraldehyde and valeraldehyde, particularly Normal butyraldehyde is preferred. Moreover, as a condensate, the condensate corresponding to the said aldehyde is mentioned. Specific examples include 2-methylpentenal, 2-ethylhexenal, 2-propylheptenal, etc., preferably 2-ethylhexenal, 2-propylheptenal, particularly preferably 2-ethylhexenal ( Ethylpropyl acrolein). This condensation reaction and dehydration can be carried out by a known method. Usually, the reaction is carried out usually at 80 to 100 ° C. using an alkaline aqueous solution, for example, 1 to 5 wt% sodium hydroxide aqueous solution as a catalyst.

The reaction solution is separated into an aqueous phase composed of an aqueous alkali solution and an oil phase composed of a condensate, and the aqueous phase is recycled as a catalyst.
According to the study by the present inventors, the alcohol obtained in the condensation step includes a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring. Specifically, when the starting aldehyde is normal butyraldehyde, the 2-ethylhexenal obtained in the condensation step contains the following aldehyde compound (I) that is considered to be formed by condensation of three molecules of NBD. It is.

  In the subsequent hydrogenation step, this compound becomes a compound having a pyran ring (II) below, and a part of the compound (II) is hydrogenated and has a dihydropyran ring (III) below. It is assumed that And even if these compounds are very little, the result of the sulfuric acid coloring test of alcohol will deteriorate remarkably.

  Compounds having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (compounds (II) and (III) above) can be changed to compounds having a corresponding tetrahydropyran ring by hydrogenation. And the produced | generated compound which has a tetrahydropyran ring does not worsen the result of the sulfuric acid coloring test of alcohol. However, under the usual hydrogenation conditions of the condensate (2-ethylhexenal), the compounds (compounds (II) and (III)) having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring are completely removed. It is difficult to hydrogenate a compound having a tetrahydropyran ring. Therefore, when the condensate (2-ethylhexenal) containing a high boiling point product (compound (I) above) obtained by condensation reaction and dehydration of NBD is hydrogenated as it is, in the resulting crude alcohol (2EH) Remains a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring that has not been hydrogenated to the tetrahydropyran ring (compounds (II) and (III) above). These compounds are difficult to separate from the alcohol (2EH) by ordinary distillation, so they are mixed into the product alcohol (2EH), and the sulfuric acid coloring test results deteriorate. Therefore, the total concentration of compounds having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (2EH) supplied to the purification step (compound having a pyran ring or dihydropyran ring) is 200 wtppm or less, It is desirable to reduce it to 100 wtppm or less, particularly preferably 50 wtppm or less.

  Examples of a method for reducing the concentration of a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring in the crude alcohol (a compound having a pyran ring or a dihydropyran ring) include rectification, flash distillation, etc. Of distillation. Specifically, the high-boiling product (compound (I) above) produced by condensation by distilling the condensate obtained in the condensation step of the aldehyde is separated from the condensate together with other high-boiling products. And a method of supplying the condensate having a reduced concentration to the next hydrogenation step. Distillation can be carried out, for example, using a distillation column having about 5 to 20 plates, at a column top temperature of 80 to 200 ° C., a column top pressure of 90 mmHg to normal pressure, and at that time, a reflux ratio of 0.2 to 10 Preferably, the removal rate of high boilers is 98% from the condensate obtained in the condensation step by purging 3% to 10% of the feed rate from the bottom of the distillation column. That is all. When a condensate containing a high boiling point is supplied to the hydrogenation step, a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring from the high boiling point in the step (the above (II), (III) If a condensate having a reduced high boiling point concentration is supplied to hydrogenation, an oxygen-containing heterocycle having a carbon-carbon double bond in the ring in the hydrogenation step. It is possible to avoid the formation of compounds having the above (compounds (II) and (III) above).

  The hydrogenation reaction of the condensate with a reduced concentration of high boilers can be carried out either in the gas phase or in the liquid phase. As a catalyst, a carrier such as diatomaceous earth, zeolite, alumina, activated carbon, nickel, chromium, What carried | supported active ingredients, such as copper and palladium, should just be used. Among them, it is preferable to use a material in which nickel and chromium are supported on diatomaceous earth, or a material obtained by reducing oxides such as chromium, copper, zinc, manganese and barium. What is necessary is just to select the temperature and pressure of reaction according to the catalyst and reaction system to be used from the range of about 40-200 degreeC and a normal pressure-15.0MPa.

  Another method for reducing the concentration of a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring in the crude alcohol (a compound having a pyran ring or a dihydropyran ring) is a condensate (2-ethyl (Hexenal) in the hydrogenation, high boiling products (compound (I)) produced by condensation and compounds having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (the above (II), (III )) To the corresponding compound having a tetrahydropyran ring. However, by hydrogenation using one kind of catalyst, hydrogenation of the condensate (2-ethylhexenal) to alcohol (2EH), high boiling point product (compound of (I) above) and ring It is possible to efficiently and simultaneously hydrogenate a compound having an oxygen-containing heterocycle having a carbon-carbon double bond (the compounds of (II) and (III) above) to a compound having a corresponding tetrahydropyran ring. Have difficulty. Therefore, a high boiling point product (compound (I)) produced by condensation in the hydrogenation step of the condensate (2-ethylhexenal) or a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring In order to hydrogenate (compounds (II) and (III)) to a corresponding compound having a tetrahydropyran ring, conditions suitable for hydrogenation of the condensate (2-ethylhexenal), and a pyran ring or dihydro The reaction conditions such as the catalyst, temperature, and pressure may be set so that the conditions are suitable for hydrogenating the pyran ring to the corresponding compound having a tetrahydropyran ring.

As the above reaction conditions, for example, the first stage hydrogenation reaction is performed at 100 to 200 ° C. and normal pressure to 15.0 MPa using a Cu—Cr catalyst, and then the second stage hydrogenation reaction is performed. A method in which the reaction is performed at 50 to 150 ° C. and 2.0 to 5.0 MPa using a Ni-based catalyst, or a first-stage hydrogenation reaction is performed at 100 to 200 ° C. using a Ni—Cr based catalyst. And a method in which the second stage hydrogenation reaction is carried out at 50 to 150 ° C. and 2.0 to 5.0 MPa using a Pd / Al ₂ O ₃ -based catalyst. It is done. The first stage and second stage hydrogenation reactions may be independently gas phase hydrogenation or liquid phase hydrogenation. “Method in which the reaction is a gas phase reaction and the second stage hydrogenation reaction is a gas phase reaction”, “The first stage hydrogenation reaction is a liquid phase reaction, and the second stage hydrogenation reaction is From the viewpoint of heat recovery, there are “methods that are liquid phase reactions” and “methods in which the first stage hydrogenation reaction is a gas phase reaction and the second stage hydrogenation reaction is a liquid phase reaction”. The first stage hydrogenation reaction is preferably carried out in the gas phase, and the second stage hydrogenation reaction is preferably carried out under mild conditions in the liquid phase from the viewpoint of reducing the production of by-products.

  In the second stage hydrogenation reaction, a reactor having a fixed bed is used as a reactor, and the hydrogenation reaction is carried out under the conditions suitable for hydrogenating the condensate until the middle of the catalyst layer. From the middle of the catalyst layer, “high boiling point product formed by condensation (compound (I)) and compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring ((II), (III) It is necessary to carry out the hydrogenation reaction under conditions suitable for hydrogenating the compound) to the corresponding compound having a tetrahydropyran ring. Specifically, “high boiling point products formed by condensation (compound of the above (I)) and compounds having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring ((II), (III) of The supply temperature to the second-stage reactor is adjusted so that the temperature at the position where "compound is suitable for hydrogenating a compound having a corresponding tetrahydropyran ring" must be the required temperature. Or “compounds having high boiling point produced by condensation (compound of the above (I)) and compounds having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (compounds of (II) and (III))” Can be achieved by adjusting the amount of the catalyst so that the necessary residence time can be maintained, for example, the residence time in a portion that is “a condition suitable for hydrogenating a compound having a corresponding tetrahydropyran ring”. By this operation, the hydrogenation rate of the condensate is increased (specifically 98% or more), and a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (having a pyran ring or a dihydropyran ring) It is possible to make the concentration of the compound) below the target value.

In the above, “in the middle of the catalyst layer” specifically means that the hydrogenation rate of the condensate is 98% or more, and the contact time with the catalyst after that position is 5 minutes or more in liquid phase hydrogenation. In phase hydrogenation, the position is 0.3 seconds or longer. Control to the conditions suitable for each of the above hydrogenations may be performed by adjusting the temperature at the inlet of the reactor or removing heat by adding a solvent.
In the case of liquid phase hydrogenation, it is preferable to set the superficial linear velocity in the reactor to 10 m / hour or more in order to suppress the drift in the reactor.

  In any of the above methods, a compound (a compound having a pyran ring or a dihydropyran ring) having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring of the crude alcohol (2EH) obtained by hydrogenation The concentration of can be 200 wtppm or less, particularly 100 wtppm or less. In the present invention, a crude alcohol (2EH) having a small content of a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring (a compound having a pyran ring or a dihydropyran ring) is distilled. To obtain purified alcohol (2EH). In the present invention, the alcohol before being subjected to distillation is referred to as “crude alcohol”, and the step of distilling the crude alcohol to obtain purified alcohol is the “purification step” in the present invention. The “purified alcohol” in the present invention. The distillation in the present invention includes rectification, flash distillation and the like. This distillation may be carried out by a conventional method, for example, using a distillation column having 20 to 50 plates, and the purity of distilled 2EH to be distilled is 99.5% or more, preferably 99. What is necessary is just to carry out so that it may become 8% or more. However, it is desirable that the operation pressure of the distillation be performed under a higher vacuum in order to produce a by-product in the distillation column or to perform distillation using a cheaper low-pressure steam.

According to the present invention, purified 2EH having a coloration of 30 APHA or less, particularly 20 APHA or less, can be easily obtained by the sulfuric acid coloring test. In addition, the sulfuric acid coloring test shall be based on the following method.
Place 100 ml of sample in a dry 300 ml stoppered flat bottom flask. While stirring the sample, 8 ml of 98 wt% concentrated sulfuric acid is added at a rate of 2 ml / min at room temperature of 30 ° C. or lower, and then the flask is stoppered and immersed in a 98 ± 2 ° C. water bath for 2 hours. After cooling to room temperature with water, 100 ml of the sample was placed in a flat color glass tube with an inner diameter of 25 mm and a height of 270 mm, and visually compared with a sample containing 100 ml of APHA color standard solution in a similar color tube, The APHA value of the color standard solution showing the same color as the sample is taken as the measurement value.

The APHA color standard solution is prepared by dissolving the following components with distilled water to make exactly 1000 ml, and this is designated as APHA500.
Potassium chloroplatinate (K ₂ PtCl ₆ ) 1.245 g
Cobalt chloride (CoCl ₂ / 6H ₂ O) 1.000 g
98% concentrated sulfuric acid 100ml
The APHA500 color standard solution is diluted with distilled water to prepare color standard solutions having various APHA values. For example, when the volume of the APHA500 color standard solution is doubled using distilled water, the APHA250 color standard solution is obtained.

The present invention will be specifically described with reference to examples.
<Example 1>
Normal butyraldehyde was mixed with a 2 wt% aqueous sodium hydroxide solution and reacted at 90 ° C. The reaction solution was allowed to stand and stratified to obtain 2-ethylhexenal.
The obtained 2-ethylhexenal was distilled using an Oldershaw 10-stage distillation apparatus under the conditions of a tower top pressure of 200 mmHg and a reflux ratio of 0.23 to remove 99% of high boiling substances. 2-ethylhexenal from which this high boiling point material was removed was subjected to liquid phase hydrogenation in the presence of a Ni—Cr catalyst at a temperature of 120 ° C. and a pressure of 4.0 MPa to obtain crude 2EH. This crude 2EH contained 8 wtppm dihydropyran compound and 0 wtppm pyran compound.

  The crude 2EH was distilled using an Oldershaw 35-stage distillation apparatus at a column top pressure of 100 mmHg and a reflux ratio of 7 to remove light boiling components in the crude 2EH, followed by distillation at a column top pressure of 100 mmHg. As a result, the high boiling component in the crude 2EH was removed and purification was performed. The purity of the obtained purified 2EH was 99.9%, the concentration of the dihydropyran compound was 1.4 wtppm, and the concentration of the pyran compound was 0 wtppm. Moreover, the result of the sulfuric acid coloring test of this purified 2EH was 5APHA.

<Example 2>
The crude 2EH obtained in Example 1 was distilled to obtain purified 2EH of dihydropyran compound 0 wtppm and pyran compound 0 wtppm. A dihydropyran compound represented by the general formula (III) was added to the purified 2EH so as to have various concentrations, and a sulfuric acid coloring test was performed. The results are shown in Table-1.

  FIG. 1 was created from the results in Table-1. If this figure is used, a sulfuric acid coloring test result can be calculated | required from the compound density | concentration of general formula (III) in 2EH.

<Example 3>
Normal butyraldehyde was mixed with a 2 wt% aqueous sodium hydroxide solution and reacted at 90 ° C. The reaction solution was allowed to stand and stratified to obtain 2-ethylhexenal.
The obtained 2-ethylhexenal was vapor-phase hydrogenated at a temperature of 190 ° C. and a pressure of 0.45 MPa in the presence of a Cu—Cr—Mn—Ba—Ni-based catalyst (Ni content: 1%). Ethyl hexenal was reacted.
This hydrogenated reaction liquid is vaporized and supplied to a fixed bed reactor filled with Ni-Zr catalyst together with hydrogen gas so that the temperature at the position of three quarters from the inlet of the catalyst layer is 140 ° C. The supply temperature was adjusted, and gas phase hydrogenation was performed at a pressure of 0.45 MPa. Further, the reaction was carried out by adjusting the feed rate of the raw material so that the gas space velocity (GHSV) in the catalyst layer after the third quarter position from the inlet was 10000 Hr ⁻¹ or less. The dihydropyran compound concentration in the crude 2EH obtained by this reaction was 129 wtppm, and the pyran compound concentration was 0 wtppm. Further, when the gas at a position of three quarters from the inlet of the catalyst layer was sampled and the condensed liquid was analyzed by gas chromatography, 2-ethylhexenal was not detected and 100% hydrogenation was performed. The dihydropyran compound concentration was 1310 wtppm, and the pyran compound concentration was 0 wtppm.

  This crude 2EH was distilled by the same method as in Example 1 to simulate the process of obtaining purified 2EH, and the concentration of the pyran compound and dihydropyran compound in the purified 2EH was determined. As a result, the purity of the obtained purified 2EH was 99.9%, the concentration of the dihydropyran compound was 67 wtppm, and the concentration of the pyran compound was 0 wtppm. Moreover, the result of the sulfuric acid coloring test of this purified 2EH is 20 APHA from FIG.

<Example 4>
Normal butyraldehyde was mixed with a 2 wt% aqueous sodium hydroxide solution and reacted at 90 ° C. The reaction solution was allowed to stand and stratified to obtain 2-ethylhexenal.
The obtained 2-ethylhexenal was subjected to liquid phase hydrogenation in the presence of a Ni—Cr catalyst at a temperature of 120 ° C. and a pressure of 4.0 MPa to react about 90% of 2-ethylhexenal.
This hydrogenated reaction solution is further supplied to a fixed bed reactor filled with a 5% Pd / Al ₂ O ₃ system catalyst, and supplied so that the temperature at a position of three quarters from the inlet of the catalyst layer becomes 130 ° C. The temperature was adjusted and liquid phase hydrogenation was performed at a pressure of 5.0 MPa. Further, the reaction was carried out by adjusting the feed rate of the raw material so that the residence time in the catalyst layer after the third quarter of the inlet was 10 minutes or more. The concentration of the crude 2EH dihydropyran compound obtained by this reaction was 0 wtppm, and the concentration of the pyran compound was 0 wtppm. Moreover, when the liquid of the position of 3/4 from the inlet of the catalyst layer was sampled and analyzed by gas chromatography, 2-ethylhexenal was not detected and 100% hydrogenated. The dihydropyran compound concentration was 384 wtppm, and the pyran compound concentration was 0 wtppm.

  This crude 2EH was distilled by the same method as in Example 1 to simulate the process of obtaining purified 2EH, and the concentration of the pyran compound and dihydropyran compound in the purified 2EH was determined. The purified 2EH thus obtained had a purity of 99.9%, the dihydropyran compound concentration was 0 wtppm, and the pyran compound concentration was 0 wtppm. Moreover, the result of the sulfuric acid coloring test of this purified 2EH is 5APHA from FIG.

<Example 5>
The process of obtaining crude 2EH by distilling crude 2EH containing 200 wtppm of dihydropyran compound and 0 wtppm of pyran compound by the same method as in Example 1 to obtain the concentration of pyran compound and dihydropyran compound in the purified 2EH. It was. As a result, the purity of purified 2EH obtained was 99.9%, the concentration of the dihydropyran compound was 105 wtppm, and the concentration of the pyran compound was 0 wtppm. Moreover, the result of the sulfuric acid coloring test of this purified 2EH is 30 APHA from FIG.

<Comparative Example 1>
Normal butyraldehyde was mixed with a 2 wt% aqueous sodium hydroxide solution and reacted at 90 ° C. The reaction solution was allowed to stand and stratified to obtain 2-ethylhexenal.
The obtained 2-ethylhexenal was subjected to liquid phase hydrogenation in the presence of a Ni—Cr catalyst at a temperature of 120 ° C. and a pressure of 4.0 MPa to obtain crude 2EH. This crude 2EH contained 878 wtppm dihydropyran compound and 0 wtppm pyran compound.
This crude 2EH was distilled by the same method as in Example 1 to simulate the process of obtaining purified 2EH, and the concentration of the pyran compound and dihydropyran compound in the purified 2EH was determined. The purified 2EH thus obtained had a purity of 99.9%, a dihydropyran compound concentration of 359 wtppm, and a pyran compound concentration of 0 wtppm. Moreover, the result of the sulfuric acid coloring test of this purified 2EH is 100 APHA or more from FIG.

The figure which shows the result of Example 2

Claims (7)

Aldol condensation and dehydration of aldehyde to give a corresponding condensate, a hydrogenation step of hydrogenating the condensate to obtain a crude alcohol, and a purification step of distilling the crude alcohol to obtain a purified alcohol In the method for producing an alcohol containing hydrogen, the concentration of the compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring in the crude alcohol is reduced by performing the hydrogenation step using at least two types of catalysts. and carbon in the ring - manufacturing method of purifying the alcohol, wherein the concentration of the compound having a heterocycle oxygenated carbon double bond to provide the following crude alcohol 200wtppm the purification process.   The production method according to claim 1, wherein the aldehyde is normal butyraldehyde, the condensate is 2-ethylhexenal, and the alcohol is 2-ethylhexanol.   The production method according to claim 1 or 2, wherein a crude alcohol having a concentration of a compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring is 100 wtppm or less is supplied to the purification step.   The method according to any one of claims 1 to 3, wherein the compound having an oxygen-containing heterocycle having a carbon-carbon double bond in the ring is a compound having a pyran ring or a dihydropyran ring.   The condensate obtained in the condensation step is distilled to reduce the content of high boilers, and then the condensate having a reduced concentration of high boilers is supplied to the hydrogenation step. 4. The production method according to any one of 4 above.   The production method according to any one of claims 1 to 5, wherein the hydrogenation step is performed in two stages, a gas phase hydrogenation step and a liquid phase hydrogenation step using a different catalyst. The manufacturing method according to any one of claims 1 to 6, wherein a sulfuric acid coloring test of purified alcohol obtained by the purification step is 30 APHA or less.

Images