JPH0813767B2 - Alcohol purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for purifying alcohol. Specifically, the present invention relates to a method for purifying an alcohol obtained by hydrogenating an aldehyde.

<Prior Art> A technology for obtaining a product alcohol by purifying an alcohol obtained by hydrogenating an aldehyde is well known.

When alcohol is used as a plasticizer raw material, an alcohol having a good sulfuric acid coloring test result is required. However, trace impurities contained in the alcohol, such as aldehydes, ketones and esters, are used in the sulfuric acid coloring test. It significantly deteriorates the grade. Therefore, trace impurities contained in alcohol are removed by distillation purification.

<Problems to be Solved by the Invention> However, it has been found that even if a trace amount of impurities in the alcohol is removed by ordinary distillation purification, an alcohol having excellent sulfuric acid coloring test results and good performance cannot be obtained.

<Means for Solving the Problems> As a result of intensive studies made by the present inventors to solve the above-mentioned problems in the purification of alcohol, when the high boiling point by-product concentration in the bottom liquid of the rectification column becomes high, the product It was found that the results of the sulfuric acid coloring test of No. 1 deteriorated significantly.

The present inventors have arrived at the present invention as a result of examining a specific solution based on this finding.

That is, in the present invention, when an alcohol product obtained by hydrogenating an aldehyde having 4 or more carbon atoms is purified by distillation, the concentration of the high boiling by-product in the bottom liquid of the distillation column is set to 30 wt.
A method for purifying alcohol, characterized in that the alcohol is distilled off while maintaining the content at not more than 100% to obtain a purified alcohol.

 The present invention will be described in more detail below.

As the raw material aldehyde used in the method of the present invention, a saturated or unsaturated aldehyde having 4 or more carbon atoms, usually 5 to 20 carbon atoms, and a mixture thereof are used.

Specifically, for example, saturated aldehyde having a linear or side chain such as n-butyraldehyde, n-pentylaldehyde, n-octylaldehyde, 2-ethylhexylaldehyde, nonylaldehyde, decylaldehyde,
Unsaturated aldehydes such as 2-ethylhexenyl aldehyde and decenyl aldehyde are mentioned.

Further, as the raw material aldehyde, those obtained by the oxo reaction of olefins are also suitably used. Specific examples of the olefins include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-
Linear α-olefins such as decene; 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-octene, 3
-Straight chain internal olefins such as octene; isobutylene,
Branched α-olefins such as 2-methyl-1-hexene, 3-methyl-1-hexene, 2-methyl-1-heptene, 3-methyl-1-heptene, 4-methyl-1-heptene; 2,3 -Dimethyl-1-hexene, 2,4-dimethyl-
Multi-branched α-olefins such as 1-hexene, 2,5-dimethyl-1-hexene, and 3,4-dimethyl-1-hexene; and double bond isomers thereof. In addition to the above, an olefin oligomer isomer mixture such as a dimer to a tetramer of lower olefins such as propylene, butene, and isobutylene, a C4 distillate obtained in a large amount by pyrolysis or catalytic cracking of hydrocarbon oil. Minute (hereinafter referred to as BB fraction)
It is also possible to use an olefin isomer mixture having a carbon number of 8 obtained by dimerizing the above, an α-olefin obtained by Ziegler low polymerization, or an α-olefin obtained by wax decomposition.

These olefins are converted into aldehydes by a conventionally known oxo reaction. As the oxo reaction conditions, the catalyst system may be either a conventional rhodium system or a cobalt system, the pressure is usually from atmospheric pressure to 300 kg / cm ² G, and the temperature is usually from 40 to 300 ° C.

The hydrogenation reaction of the above aldehyde can be carried out by a usual method. Any conventionally known catalyst can be used. For example, a carrier such as Celite or diatomaceous earth carrying nickel, chromium, copper, calcium, magnesium or the like can be used.

The aldehyde is hydrogenated to the corresponding alcohol by the hydrogenation reaction. Regarding the hydrogenation reaction conditions, the pressure is usually normal pressure or higher, preferably normal pressure to 100 atm, and the temperature is usually room temperature or higher, preferably 40 to 200 ° C.

The conversion rate of the aldehyde in the hydrogenation reaction is not critical, but it is preferably in the range of 80 to 99.99%.

If the conversion rate is less than 80%, there are many unreacted substances, and the amount of recirculation for use in re-reaction increases, which is not economically advantageous. Further, when the conversion rate exceeds 99.99%, it is not preferable because it is necessary to increase the reaction temperature, the reaction time, the amount of the catalyst, and the like, and accordingly increase the undesirable side reaction products and the like.

The crude alcohol thus obtained is subjected to distillation purification.

Various methods are used as the distillation purification process.
That is, for example, first, a light boiling substance such as unreacted aldehyde is distilled off, and then a desired product alcohol is distilled off in a rectification column, or a middle distillation of the distillation column is performed to remove light alcohol in one distillation column. There are methods such as boiling separation and high boiling point separation.

The present invention can be applied to any of these methods. In the distillation purification, the concentration of high boiling by-products in the bottom liquid of the distillation column is 30% by weight or less, preferably 20% by weight.
Hereafter, it is important to distill alcohol while maintaining it in the range of preferably 1 to 10% by weight.
It is carried out under the conditions of 60 plates, a reflux ratio of 0.05 to 50, and a column bottom temperature of 80 to 180 ° C.

Further, the conditions of the distillation column for separating the light boiling substances such as the above-mentioned aldehyde are usually operated under the condition that the aldehyde and the target alcohol are separated, and the pressure is usually reduced to several millimeters of mercury column to atmospheric pressure, theoretical plate number of 5 to 90. Stage, reflux ratio is 0.1-100.

Regarding the conditions of the distillation column for separating the high-boiling substance, the distillation column is usually operated under a reduced pressure of several millimeters of mercury column to normal pressure, theoretical plate number of 1 to 20 and reflux ratio of 0 (single distillation) to 50 plates.

Although it cannot be said that the chemical influence of the high boiling point substance on the hue of the alcohol has been completely clarified, the hue is poor even if the high boiling point substance is sufficiently distilled and purified to 5 ppm or less in the product alcohol. May be. Therefore, it is expected that the high boiling point substance itself does not affect, but that some kind of color deterioration product is generated as a relatively light boiling component due to thermal decomposition of the unstable high boiling point substance. The purified alcohol obtained is used as a raw material for solvents, plasticizers, detergents, surfactants, etc., and is used for esterification, especially when it is esterified with an acid such as phthalic anhydride or adipic acid by a conventional method. Since the hue is particularly important in the quality of the alcohol, the alcohol obtained by the present invention is excellent.

The hue is generally measured by the sulfuric acid coloring test method.

The sulfuric acid coloring test method includes Monsanto method, Eastman method, Sekisui method, etc., but all of them differ only in fine conditions and the main operation is the same, and Monsanto method is generally widely used. The Monsanto method was also adopted in the examples described later, and the measuring method is shown below.

Sample 100 in a washed and dried 300 ml flat bottom flask with stopper
Add ml. 98wt at room temperature below 30 ℃ while stirring the sample
Add 8 ml of concentrated sulfuric acid% at 25 ml puret at a rate of 2 ml / min. The flask is stoppered and immersed in a water bath at 98 ± 2 ° C for 2 hours. Then, after cooling to room temperature with water, the sample was transferred to a flat-bottom glass colorimetric tube having an inner diameter of 25 mm and a height of 270 mm (100 ml), and visually compared with the same amount of APHA color standard solution in the same colorimetric tube. The APHA value of the same color is used as the measured value.

 The composition of the APHA stock solution is as follows.

Put potassium chloroplatinic acid (K ₂ PtCl ₆₎ 1.245g of cobalt chloride _{(CoCl 2 · 6H 2 O)} 1.000g 98% or more concentrated sulfuric acid 100ml to 1000ml ml volumetric flask, and dissolved by adding distilled water, with distilled water Make exactly 1000 ml. This liquid is APHA
500, and then proportionally diluted with distilled water to obtain a low APHA color standard solution.

Generally, an APHA value of about 5 to 25 is desirable as a product alcohol.

〔Example〕

Next, specific examples of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Examples-1 to 4 and Comparative Examples-1 to 2 (1) Synthesis of olefin having 8 carbon atoms C ₄ fraction (composition: isobutene 6 after removal of butadiene and isobutene from BB fraction obtained from naphtha cracker) % By weight, 43% by weight of 1-butene, 25% by weight of 2-butene, 25% by weight of butanes and 1% by weight of others) were dehydrated with a molecular sieve 13X. Then, in a 10-volume SUS induction stirring autoclave, under a nitrogen atmosphere, 4 kg of the C ₄ fraction after dehydration described above, 5.5 g of nickel octanoate n-hexane solution (Ni content 6 wt%) and ethylaluminum dichloride. 11.3 g was charged and the dimerization reaction was carried out at 40 ° C. for 7 hours.

After the reaction, 340 g of a 5 wt% H ₂ SO ₄ aqueous solution was added to deactivate the catalyst and then separated into liquids, and then purified by distillation with a 15-stage distillation column to obtain an octene fraction. The distillation in this case was carried out in a batch system, the reflux ratio was 3.0, and the yield of the octene fraction obtained by the distillation was 95%.

 The above operation was repeated 3 times.

(2) Synthesis of alcohol having 9 carbon atoms In a SUS autoclave with a volume of 10 under a nitrogen atmosphere,
The octene fraction obtained in (1) above (2.0 kg), rhodium acetate aqueous solution (0.3 g (containing 10% as Rh metal)) and triphenylphosphine oxide (1.63 g) were added, and the total pressure was 160 kg / with oxo gas with H ₂ / CO = 1. It was held at cm ² G, and a hydroformylation reaction was carried out at a reaction temperature of 130 ° C. After 5 hours, the absorption of gas disappeared, so the reactor was rapidly cooled and the oxo gas was released.
The whole amount of the reaction solution was taken out, and then aldehyde and alcohol were obtained by simple distillation under reduced pressure of 5 to 10 mmHg. The conversion of the octene fraction in the hydroformylation reaction was 95%, the total yield of aldehyde and alcohol was 93%, and the remaining 2% was mainly high boiling by-products. The total yield of aldehyde and alcohol in simple distillation was about 97%.

Next, in a volume 10 SUS autoclave, the total amount of the liquid obtained from the simple distillation and 160 g of the nickel-supported solid catalyst were charged under a nitrogen atmosphere, the total pressure was maintained at 90 kg / cm ² G with hydrogen gas, and the reaction was performed at 100 ° C. Hydrogenation reaction was carried out at a temperature.

After 8 hours, the gas absorption was completed, so that the mixture was rapidly cooled, the pressure of the hydrogen gas was released, the whole amount of the reaction liquid was taken out, and the solid catalyst was removed by passing to obtain a crude alcohol.

 As a result of the hydrogenation reaction, the conversion rate of aldehyde was 99.8% and the high boiling rate was 1.6%.

(3) Purification of C ₉ alcohol The crude C ₉ alcohol obtained in (2) above was treated with an inner diameter of 35 mm ×
It is supplied to the 20th stage of the 30-stage Oldershaw distillation column (A) [light boiling column], the reflux ratio is 15, the column top pressure is 80 mmHg, and the column top temperature is about 11
Distillation under conditions of 0 ℃, bottom temperature of about 140 ℃, feed rate of 300 ~ 400 ml / hr, distill off the light boiling substance containing unreacted aldehyde from the top of the tower, the bottom liquid from the bottom of the column 35 mm × Under the conditions of a reflux ratio of 0.5, a top pressure of 10 mmHg, a top temperature of about 90 ° C, and a bottom temperature shown in Table 1, the 10th stage of a 20-stage Older Shoe distillation column (B) [product column] is supplied. It was distilled and purified alcohol was distilled from the top of the column to obtain it. Bottom liquid from the bottom of the column (concentration of high boiling by-products in the bottom liquid was variously changed as shown in Table-1)
Is an Oldershaw distillation column (C) with an inner diameter of 35 mm x 20 stages
Supply to the 10th stage of [high boiling tower], reflux ratio 1 to 5, tower top pressure
Distillation under conditions of 10 mmHg, column top temperature of about 100 ° C, and column bottom temperature of 130 to 180 ° C to distill alcohol from the column top and circulate it to the distillation column (A). The effluent was appropriately withdrawn.

The hue of the obtained purified alcohol was measured by performing a sulfuric acid coloring test by the Monsanto method. Table 1 shows the properties of the purified alcohol.

[Effect of the Invention] According to the method of the present invention, a purified alcohol having an improved hue can be obtained. The obtained alcohol is useful as an alcohol used as a raw material for solvents, plasticizers, detergents, surfactants and the like.

Claims (1)

[Claims] 1. A method for distilling and purifying an alcohol product obtained by hydrogenating an aldehyde having 4 or more carbon atoms, while maintaining the concentration of a high boiling by-product in the bottom liquid of a distillation column at 30 wt% or less. A method for purifying alcohol, which comprises distilling alcohol to obtain purified alcohol.