JPH0580458B2 - - Google Patents

Description

[Detailed description of the invention]

Object of the Invention Industrial Application Field The present invention relates to a method for separating _C3 or higher alcohols from a solution containing _C3 or higher alcohols. It relates to a method suitable for energy-saving and low-cost separation of oils (including amyl alcohol, butyl alcohol, etc.), and more generally including alcohols with C2 _or less such as methyl alcohol and ethyl alcohol. A solution containing at least two types of alcohol components (or a group of components) containing C ₃ or higher alcohols
The present invention relates to a method for separating _C3 or higher alcohols from an aqueous solution of C3 or _higher alcohols. BACKGROUND ART In the process of obtaining ethyl alcohol from fermented alcohol or its crude distilled aqueous solution, a method for separating fusel oil (including amyl alcohol, butyl alcohol, etc.) in an energy-saving and low-cost manner has become a technical issue. Conventionally, fusel oil has been separated by distillation, but distillation consumes a lot of energy. As a method for extracting alcohol from an aqueous alcohol solution using an extraction method using a solvent, there is a liquid-liquid extraction method using CO ₂ or a supercritical extraction method (Japanese Patent Application Laid-Open No. 56-56201).
There is a method using fluorocarbon (such as Freon-11) as an extraction solvent that satisfies specific physical properties (Japanese Patent Application Laid-open No. 125693/1982), but these methods are not necessarily satisfactory separation methods. Gataku, again 2
There is no description of separating a mixed alcohol consisting of more than one type of alcohol component by an extraction operation. Problems to be Solved by the Invention The present invention is capable of efficiently separating C3 _or higher alcohols from a solution containing C3 or higher alcohols, and is capable of efficiently separating C3 _or higher alcohols from a solution containing C3 or higher alcohols. An object of the present invention is to provide a method for separating a mixed alcohol consisting of two or more types of alcohol components in an energy-saving and low-cost manner. Means for Solving the Constituent Problems of the Invention The alcohol separation method of the present invention comprises contacting a solution containing a _C3 or higher alcohol with liquid 1,1-difluoroethane to remove at least one
It consists of extracting the species C ₃ or higher alcohol and then removing the 1,1-difluoroethane from the extraction phase. Alcohols with C3 or _higher include propyl alcohol, butyl alcohol, amyl alcohol,
Examples include octyl alcohol, branched alcohol, and dihydric alcohol. 1,1-Difluoroethane (DFE) is a type of fluorocarbon, and has a heat of vaporization of 78.27 cal/g (boiling point -24°C) and a specific heat of 0.418 cal/g·°C. The present inventors measured the partition coefficients of various alcohols in a 1,1-difluoroethane-water system and obtained the results shown in FIGS. 1 and 2. The distribution coefficient is expressed by the following formula. Partition coefficient (m) = alcohol concentration in DFE (w
t%)/Alcohol concentration in the aqueous phase (wt%) Figure 1 shows the respective partition coefficients at a pressure of 13 atm and a temperature of 50°C, where the horizontal axis is the alcohol concentration (wt%) in the aqueous phase and the vertical axis is represents the distribution coefficient (m),
〓 mark is methyl alcohol, □ mark is ethyl alcohol, △ mark is n-propyl alcohol, ▽ mark is n-
Butyl alcohol and ○ mark represent n-amyl alcohol. However, the distribution coefficients marked with □, △, △, and ▽ are the values shown on the right vertical axis, and the distribution coefficients marked with ○ are the values shown on the left vertical axis. Figure 1 shows that in the 1,1-difluoroethane-water system, n-propyl alcohol, n-
It can be seen that butyl alcohol and n-amyl alcohol have significant differences in their partition coefficients. Figure 2 shows the change in the partition coefficient when the extraction pressure is changed, where the horizontal axis shows the alcohol concentration (wt%) in the aqueous phase, and the vertical axis shows the partition coefficient (m).
The □, △, and ○ marks are ethyl alcohol, n-propyl alcohol, and n-amyl alcohol at 13 atm and 50°C, respectively, as shown in Figure 1. The ■, ▲, and ● marks are the pressure, respectively.
Ethyl alcohol at 60atm, concentration 50℃, n
-Propyl alcohol and n-amyl alcohol, the x mark represents ethyl alcohol at a pressure of 100 atm and a concentration of 50°C. However, the distribution coefficients marked with ○ and ● are the values shown on the left vertical axis, and the others are the values shown on the right vertical axis. According to Figure 2, the partition coefficient of ethyl alcohol is
Almost no change due to pressure is observed between 13 atm and 100 atm, but n-propyl alcohol and n-
It can be seen that the distribution coefficient of amyl alcohol increases with increasing pressure, and the difference from the distribution coefficient of ethyl alcohol becomes even larger. The present invention utilizes the above-mentioned difference in the distribution coefficients of various alcohols in a 1,1-difluoroethane-water system to separate the alcohol from a solution containing C3 _or higher alcohol.
the ratio of difluoroethane to alcohol mixture;
By appropriately selecting the ratio of 1,1-difluoroethane and water and the extraction pressure, etc., it is possible to obtain alcohols with a C3 or higher content consisting of at least two types of alcohol components, including alcohols with a _C2 or lower content such as methyl alcohol and _ethyl alcohol. Separating a solution containing alcohol into two components (or groups of components), or
Alcohols with C ₃ or more can be separated from aqueous solutions of alcohols with C ₃ or more. Specifically, removal of fusel oil from fermentation alcohol or its crude distillate aqueous solution, separation of alcohols with C3 or more from a mixed solution of ethanol and alcohol with _C3 or more, and separation of alcohols with _C3 or more from a mixed solution of methanol and alcohol with _C3 or more. Separation of alcohols with _C3 or more, separation of ethanol and a mixture of alcohols with C3 _or more from a mixed solution of methanol, ethanol, and alcohols with C3 _or more, alcohols with _C3 or more from a mixed solution of methanol, ethanol, and alcohols with C3 _or more Separates a mixed solution of _C3 or higher alcohols such as propyl alcohol, butyl alcohol, amyl alcohol into two components or component groups, Aqueous solutions of _C3 or higher alcohols such as propyl alcohol, butyl alcohol, amyl alcohol, etc. It is possible to effectively perform operations such as separating each alcohol from Note that the alcohol mixed solution may be an aqueous solution or a solution consisting only of alcohol. The extraction temperature with 1,1-difluoroethane is 20
~80℃, preferably 20-50℃, extraction pressure 1,1
−More than the vapor pressure of difluoroethane ~ about 100 atm,
Preferably 5 to 20 atm, solvent ratio (1,1 difluoroethane supply amount/alcohol-containing solution amount) is 0.1
-10, preferably 0.5-5. When the alcohol solution to be separated is a mixture of only alcohols, it is desirable to bring the liquid extracted with 1,1-difluoroethane into contact with a back-extracting agent in order to further improve separation performance. Water is preferred as a back-extracting agent because it is easy to handle, harmless, and inexpensive. Furthermore, even when the alcohol mixture to be separated contains water, it is often preferable to further add water as a back-extracting agent in order to improve the separability when separating into two alcohol components (or component groups). . For example, if the mixed alcohol concentration of the raw materials is
When it is about 10%, it is better to further add about 20% of water to the amount of the raw alcohol-containing solution. When the solution containing an alcohol of _C3 or higher is a mixture of at least two alcohol components including an alcohol of _C2 or lower, the mixture is brought into contact with liquid 1,1-difluoroethane in the presence of water. After performing the extraction operation, the aqueous phase and the 1,1-difluoroethane phase are separated, at least one alcohol component is recovered in a state dissolved in the aqueous phase, and the 1,1-difluoroethane phase is recovered from the 1,1-difluoroethane phase.
-Difluoroethane is vaporized to recover other alcohol components dissolved in the 1,1-difluoroethane phase, and the vaporized 1,1-difluoroethane is liquefied and recycled to the extraction step for reuse. FIG. 3 shows an example of a process flow sheet for carrying out the method of the present invention, and a specific embodiment of the present invention will be described using a case where fermentation alcohol (ethyl alcohol containing fusel oil) is used as a raw material as a representative example. Fermentation alcohol is introduced from line 2 into the middle part of extraction column 1, 1,1-difluoroethane (DFE) is introduced from line 3 at the bottom side of the column, and water is introduced from line 4 at the top side of the column to perform countercurrent multistage liquid-liquid extraction. . The extract derived from the top of the extraction column 1 is preheated by heat exchangers 5, 6, and 7, DFE is vaporized and separated by a solvent separator 8, and fusel oil is discharged from a line 9. The water that was mixed in is line 1
Discharge from 0. DFE vaporized in the solvent separator 8 is pressurized in the compressor 11, liquefied by cooling in the heat exchanger 6, and recycled to the extraction column 1 via the line 12 for use. On the other hand, the raffinate is discharged from the bottom of the extraction column 1 and separated into DFE vapor and an ethyl alcohol aqueous solution in an ethyl alcohol aqueous solution separator 13. The separated aqueous ethyl alcohol solution is recovered through line 14. The separated DFE vapor is collected in a gas holder 15, sucked by a vacuum pump 16, and cooled by a heat exchanger 5. This DFE vapor is further pressurized by a compressor 17, cooled and liquefied by a heat exchanger 7, and is circulated to the extraction column 1 via a line 18 for use. In this way, the ethyl alcohol component is recovered as an aqueous solution, and fusel oil (amyl alcohol,
(including propyl alcohol, etc.) can be separated. Since the mash obtained by fermentation usually contains 1 to 3% sludge, an evaporation tower or the like may be installed to remove the sludge before extraction, but if the present invention is implemented, the sludge will be precipitated during extraction. Therefore, if this is allowed to settle and discharged from the bottom of the extraction column through line 19, it will be more energy efficient. In addition, when separating a C ₃ or higher alcohol from an aqueous solution, it can be similarly carried out by introducing the alcohol-containing aqueous solution as a raw material from the top side of the extraction tower without supplying water to the extraction tower. Furthermore, by carrying out the method of the present invention in multiple stages, C ₃
It also becomes possible to separately separate a plurality of alcohols in a solution containing the above alcohols. Examples 1 and 2 Ethyl alcohol containing fusel oil was treated according to the process flow shown in FIG. Table 1 shows the raw material composition, operating conditions, and operating results.

【table】

[Table] Example 3 An aqueous ethyl alcohol solution containing a small amount of medium boiling point alcohol such as n-propyl alcohol was treated according to the process flow shown in FIG. DFE was vaporized and separated from the raffinate drawn from the bottom of the extraction column using an ethyl alcohol aqueous solution separator to obtain an ethyl alcohol aqueous solution from which medium-boiling point alcohol had been removed. Table 2 shows the raw material composition, operating conditions, and operating results.

【table】

[Table] Example 4 Recovery of n-butanol from a 2wt% n-butanol aqueous solution was performed according to the process flow shown in FIG. Note that water was not supplied to the extraction tower since it contained no alcohol other than n-butanol. The operating conditions and operating results are shown in Table 3.

[Table] Effects of the invention (1) Significant energy savings compared to the distillation method. (2) Since 1,1-difluoroethane liquefies at 30°C and 6 atmospheres, liquid-liquid extraction can be performed at a pressure of about 5 to 15 atmospheres, making it possible to reduce the weight of equipment. (3) 1,1-difluoroethane has extremely low toxicity and is safe to handle. (4) When used to remove fusel oil from fermentation alcohol, the partition coefficient for fusel oil is high and the selectivity for ethyl alcohol is extremely high, so it is possible to reduce the amount of extraction solvent used and downsize the equipment.

[Brief explanation of the drawing]

Figure 1 shows the partition coefficients of various alcohols in a 1,1-difluoroethane-water system at 13 atm and 50°C, where the horizontal axis shows the alcohol concentration (wt%) in the aqueous phase and the vertical axis shows the partition coefficient (m). The 〓 mark represents methyl alcohol, the □ mark represents ethyl alcohol, the △ mark represents n-propyl alcohol, the ▽ mark represents n-butyl alcohol, and the ○ mark represents n-amyl alcohol.
Figure 2 shows the change in the partition coefficient when the extraction pressure is changed. The horizontal axis shows the alcohol concentration in the aqueous phase (wt%), the vertical axis shows the partition coefficient (m), and □
The marks, △, and ○ are the same as those shown in Figure 1, ethyl alcohol, n-propyl alcohol, and n-amyl alcohol at 13 atm and 50℃, and the ■, ▲, and ● marks are the pressure, respectively.
Ethyl alcohol at 60atm, concentration 50℃, n
-Propyl alcohol and n-amyl alcohol, x represents ethyl alcohol at a pressure of 100 atm and a temperature of 50°C. FIG. 3 is a diagram showing an example of a process flow sheet for implementing the present invention.

Claims (1)

[Scope of Claims] A solution containing a 1 C ₃ or higher alcohol is brought into contact with liquid 1,1-difluoroethane to extract at least one C ₃ or higher alcohol from the solution, and then a 1,1 or higher alcohol is extracted from the extraction phase. - A method for separating alcohols consisting of removing difluoroethane. 2. The method for separating alcohol according to claim 1, wherein the solution containing an alcohol with a carbon content of ₃ or more also contains an alcohol with a carbon content of ₂ or less. 3. The alcohol separation method according to claim 1 or 2, wherein the solution containing alcohol of 3 C ₃ or more is an aqueous solution. 4 The solution containing an alcohol of C ₃ or more is a mixture of at least two types of alcohol components including an alcohol of C ₂ or less, and the mixture is brought into contact with liquid 1,1-difluoroethane in the presence of water. After performing the extraction operation, the aqueous phase and the 1,1-difluoroethane phase are separated, at least one alcohol component is recovered in a state dissolved in the aqueous phase, and the 1,1-difluoroethane phase is recovered from the 1,1-difluoroethane phase.
A patent claim consisting of vaporizing difluoroethane to recover other alcohol components dissolved in the 1,1-difluoroethane phase, and liquefying the vaporized 1,1-difluoroethane and recycling it to the extraction step for reuse. A method for separating alcohol according to item 1, item 2, or item 3. 5. The solution containing an alcohol of C ₃ or more is a mixture of at least two types of alcohol components including an alcohol of C ₂ or less, and the mixture is introduced into the middle part of a multistage extraction column, ,1-
Separation of alcohol as set forth in claim 4, which comprises introducing difluoroethane and water from the top side of the column to bring them into liquid contact, and extracting an aqueous phase from the bottom of the column and a 1,1-difluoroethane phase from the top of the column. Method. 6. The alcohol separation method according to claim 2, 3, 4, or 5, wherein the solution containing alcohol of 6 C ₃ or more is a fermented alcohol or a crude distilled aqueous solution thereof.