WO2016080531A1 - Method for concentrating and dehydrating butanol - Google Patents

Method for concentrating and dehydrating butanol Download PDF

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WO2016080531A1
WO2016080531A1 PCT/JP2015/082741 JP2015082741W WO2016080531A1 WO 2016080531 A1 WO2016080531 A1 WO 2016080531A1 JP 2015082741 W JP2015082741 W JP 2015082741W WO 2016080531 A1 WO2016080531 A1 WO 2016080531A1
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butanol
extraction
extraction solvent
temperature
liquid
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PCT/JP2015/082741
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French (fr)
Japanese (ja)
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堀添　浩俊
洋 町田
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国立大学法人名古屋大学
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
    • C07C31/02—Monohydroxylic acyclic alcohols
    • C07C31/12—Monohydroxylic acyclic alcohols containing four carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
    • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
    • C07C29/86—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by liquid-liquid treatment

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  • the present disclosure relates to a method for concentrating and dehydrating butanol.
  • biobutanol Compared with bioethanol, biobutanol has excellent properties as an automobile fuel, such as high calorific value, low hygroscopicity, no effect on gasoline vapor pressure increase, and addition to gasoline and light oil.
  • genetically modified yeast is required for ethanol fermentation of C5 sugar, but there are many advantages such as the ability to use existing yeast in butanol fermentation, and it has attracted attention as post-ethanol.
  • the concentration of biobutanol produced by saccharification and fermentation of biomass such as sugarcane, corn, grass, and wood is dilute at 0.5 to 1.0 wt% due to strong fermentation inhibition of butanol, and the rest is moisture. It is.
  • Biobutanol is an aqueous solution mainly composed of normal butanol or isobutanol.
  • concentration of normal butanol is about 1.0 wt%
  • acetone is about 0.6 wt%
  • ethanol is about 0.1 wt%.
  • An aqueous solution of In recent years, yeast having resistance to butanol fermentation inhibition has been developed by genetic recombination, and the butanol concentration in biobutanol has been improved, and a butanol fermentation concentration of about 2.0 to 3.0 wt% has been achieved. It is feasible.
  • the energy required for the method (1) is as low as about 5 MJ / kg. However, for practical use, it is necessary to solve the problems of improving the permeation rate of the film, film deterioration, and contamination of the film due to impurities inside and on the surface. It is thought that there is. Further, the energy required for the method (2) is as low as about 5 MJ / kg, but 2 octanol is highly toxic to yeast, and 2 octanol dissolved in water must be extracted and separated with a harmless solvent. A complex system with two units and two distillation columns is required.
  • One aspect of the present disclosure is to provide a novel butanol concentration and dehydration method.
  • a method for concentrating and dehydrating butanol includes an aqueous butanol solution and an extraction solvent selected from the group consisting of butane, isopentane, and normal pentane under conditions of an extraction temperature T and an extraction pressure P.
  • An extraction step of bringing the extraction solvent and the extracted butanol-containing extract into contact with each other; and extracting the extract by distillation, butanol, water, and a gas phase component containing the extraction solvent, and butanol Separating into a liquid phase component, extracting butanol contained in the gas phase component with
  • the extraction temperature T is in the range of 100 to 250 ° C., and when the critical temperature of the extraction solvent is Tc, the extraction temperature T is 0.95 Tc or less, and the extraction pressure P is the extraction temperature P It is equal to or higher than the vapor pressure of the extraction solvent at T.
  • the method of concentrating and dehydrating butanol according to the present disclosure can reduce the energy required for concentrating and dehydrating butanol. Further, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of a permeable membrane. In addition, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of 2 octanol, and therefore a step of extracting and separating 2 octanol with a harmless solvent is not essential.
  • FIG. 1 is a table showing the main physical properties of paraffinic hydrocarbons having 1 to 10 carbon atoms and cyclic hydrocarbon compounds having 6 to 8 carbon atoms.
  • FIG. 2 is a graph showing the relationship between temperature and butanol selectivity.
  • FIG. 3 is a graph showing the relationship between temperature and butanol solubility.
  • FIG. 4 is an explanatory diagram showing the configuration of an apparatus used for the butanol concentration and dehydration method.
  • FIG. 5 is a vapor-liquid equilibrium diagram of normal butanol (NBA) / water system.
  • FIG. 6 is a table showing experimental conditions and experimental results of the butanol concentration and dehydration method.
  • FIG. 7 is a graph showing the relationship between the butanol concentration in the butanol aqueous solution and the concentrated dehydration heat energy.
  • the butanol aqueous solution used in the present disclosure is an aqueous solution mainly containing normal butanol or isobutanol as a component other than water, and contains 1 to 80% normal butanol or isobutanol, and 99 to 20% water, preferably, It contains 1 to 3% normal butanol or isobutanol and 99 to 7% water.
  • biobutanol obtained by fermentation is targeted, but an aqueous solution of butanol obtained by recovery from a synthetic chemical reaction step, a washing step, or the like may be used.
  • the biobutanol may be an aqueous solution of butanol obtained from fermentation by ABE fermentation (acetone-butanol-ethanol (ABE) fermentation: synthesizing acetone, normal butanol, ethanol from starch) genetically modified yeast. Moreover, the butanol aqueous solution obtained by a catalyst synthesis reaction from bioethanol may be sufficient.
  • the extraction solvent used in the present disclosure is preferably a hydrophobic solvent having high butanol solubility, high butanol selectivity, and capable of extracting a high concentration of butanol. Furthermore, when the extracted waste water discharged after the extraction step is recycled for use in the biobutanol fermentation step, the extraction solvent is preferably non-toxic.
  • the extraction solvent does not dissolve in the extraction waste water (for example, water).
  • an extraction solvent that does not form an azeotrope with butanol and has a lower boiling point than butanol is preferred.
  • azeotrope is formed, butanol is entrained in the extraction solvent and the loss of butanol increases. Further, when the boiling point is higher than that of butanol, it becomes difficult to separate the extraction solvent and butanol.
  • paraffinic hydrocarbons that meet these conditions and hardly dissolve in water and have low toxicity to yeast.
  • paraffinic hydrocarbons have low butanol solubility and have been made unsuitable as extraction solvents.
  • the inventor of the present disclosure increases the vapor pressure when the temperature of butanol is increased. Particularly, in the vicinity of the boiling point of butanol (boiling point of isobutanol: 381K, boiling point of normal butanol: 390.9K), the temperature increases as an index. In particular, it was found that the solubility of butanol in the extraction solvent increases rapidly as the vapor pressure increases.
  • Paraffinic hydrocarbons are hydrophobic, and their density rapidly decreases as they approach the critical temperature. Therefore, it is preferable to use paraffinic hydrocarbons whose critical temperature is higher than about 100 ° C. near the boiling point of butanol as the extraction solvent. .
  • Fig. 1 shows the main physical properties of paraffinic hydrocarbons having 1 to 10 carbon atoms and cyclic hydrocarbon compounds having 6 to 8 carbon atoms.
  • the critical temperature of methane, ethane, and propane is lower than the boiling point of butanol, which is not preferable as an extraction solvent.
  • Cyclic hydrocarbons are not preferred because they form an azeotrope with butanol. Paraffin hydrocarbons having C8 (carbon number 8) or higher are not preferable because their boiling points are higher than butanol. Benzene is not preferred because it is carcinogenic. C7 and C8 paraffin hydrocarbons are not preferable because they form a non-negligible azeotrope with butanol.
  • the extraction solvent is at least one selected from the group consisting of butane, isopentane, and normal pentane.
  • the extraction temperature T is basically preferably as high as possible. However, if the extraction temperature T exceeds about 250 ° C., the concentration of concentrated butanol decreases and the thermal decomposition reaction of butanol proceeds. is there. Furthermore, from the viewpoint of keeping the density of the extraction solvent high, the critical temperature TR (extraction temperature T / extraction solvent critical temperature Tc: temperature is absolute temperature K) is set to 0.95 or less, and the extraction pressure P is set to It is desirable that the vapor pressure be equal to or higher than the extraction temperature T. That is, the extraction temperature T is 0.95 Tc or less.
  • the pressure dependence of the density of the extraction solvent is low, the effect of increasing the solubility and selectivity by increasing the pressure is small, and the pressure of the extraction tower is ⁇ 0.1 by the operation of the pressure control valve. Since it fluctuates by about ⁇ 0.2 MPa, it is preferable that the extraction pressure P be 1.1 times or more and 1.2 times or less the vapor pressure of the extraction solvent at the extraction temperature so that it never becomes less than the vapor pressure. Higher pressure than this is not preferable because the disadvantage of increased equipment cost due to increased apparatus thickness and increased operating cost due to increased pump power is dominant.
  • the extraction temperature T is in the range of 100 to 250 ° C., and the extraction temperature T is 0.95 Tc or less.
  • the extraction pressure P is not less than the vapor pressure of the extraction solvent at the extraction temperature T and not more than 1.2 times the vapor pressure.
  • the extraction pressure P is 4 MPa
  • the extraction temperature T is 40 to 170 ° C.
  • a normal butanol concentration of 1.0 wt% aqueous solution (an aqueous solution having a normal butanol concentration of 1.0 wt% at equilibrium) and a butane solvent (extraction solvent concentration).
  • An example was added to perform the extraction step, and the butanol concentration and water concentration in the butane solvent after extraction were analyzed.
  • the measurement result of butanol selectivity (butanol concentration) is shown in FIG. 2, and the measurement result of butanol solubility is shown in FIG.
  • the butanol selectivity is the amount of butanol contained in the gas phase (that is, the solvent-free butanol concentration) when the total amount of butanol and water contained in the gas phase is 100.
  • Butanol solubility is the concentration of butanol in the gas phase.
  • a preferable extraction temperature T that can simultaneously increase both the butanol selectivity and the butanol solubility is 110 to 130 ° C.
  • the critical temperature TR of the extraction solvent that can simultaneously increase both the butanol selectivity and the butanol solubility is in the range of 0.90 to 0.948.
  • the configuration of the apparatus 100 used for the butanol concentration and dehydration method and the configuration of the apparatus 100 used for the butanol concentration and dehydration method will be described with reference to FIG.
  • the apparatus 100 includes an extraction tower 1, a distillation tower 2, a water separation tank 3, a compressor 4, heat exchangers 5, 6, 7, 8, 11, an intermediate heater 9, a reboiler 10, a pressure And control devices 12, 13, and 14. Moreover, each part of the apparatus 100 is connected by piping, and a substance can be transferred via the piping.
  • S1 to S24 are stream numbers representing the transfer of substances via pipes.
  • the extraction tower 1 is a vertical cylindrical container, and includes a gas-liquid contact portion 1a therein.
  • a gas-liquid contact portion 1a As the gas-liquid contact portion 1a, a shelf, an irregular packing, a regular packing, or the like generally used for increasing the gas-liquid contact efficiency can be used.
  • the distillation tower 2 is a vertical cylindrical container, and includes an upper gas-liquid contact part 2a, an intermediate gas-liquid contact part 2b, and a lower gas-liquid contact part 2c.
  • the configurations of the upper-layer gas-liquid contact portion 2a, the middle-layer gas-liquid contact portion 2b, and the lower-layer gas-liquid contact portion 2c are the same as those of the gas-liquid contact portion 1a.
  • a liquid intermediate holding part 2d exists between the middle gas-liquid contact part 2b and the lower gas-liquid contact part 2c.
  • the liquid intermediate holding part 2d holds the liquid flowing down from above up to a certain amount.
  • the amount of liquid held in the liquid intermediate holding part 2d exceeds a certain amount, the liquid overflows and flows down below the liquid intermediate holding part 2d.
  • the temperature in the extraction tower 1 and the distillation tower 2 is controlled by a temperature control mechanism (not shown). Moreover, the pressure in the extraction tower 1, the distillation tower 2, and the water separation tank 3 is controlled by the pressure control devices 12, 14, and 13, respectively.
  • extraction temperature T within a range of 100 to 250 ° C. and 0.95 Tc or less.
  • Tc is the critical temperature of the extraction solvent.
  • Extraction pressure P Being equal to or higher than the vapor pressure of the extraction solvent at the extraction temperature T.
  • the biobutanol aqueous solution flowing down from the upper part of the extraction tower 1 and the extraction solvent rising from the lower part of the extraction tower 1 are in countercurrent contact, and the butanol in the biobutanol aqueous solution is extracted into the extraction solvent.
  • An extract containing the extracted butanol and the extraction solvent is taken out from the upper part of the extraction tower 1 to S6.
  • water is taken out from the bottom of the extraction tower 1 to S5. This water is substantially free of butanol and extraction solvent.
  • the extract taken from the upper part of the extraction tower 1 is supplied from S9 to the distillation tower 2 via the heat exchangers 8 and 11.
  • the extract is separated in the distillation column 2 into a gas phase component containing butanol, water, and an extraction solvent, and a liquid phase component containing butanol.
  • the liquid phase component containing butanol flows down below the distillation column 2 and is taken out from the bottom of the distillation column 2 to S16.
  • a liquid extraction solvent is supplied to the distillation tower 2 from S10.
  • the liquid extraction solvent flows down while absorbing butanol in the gas phase at the upper gas-liquid contact part 2a, and flows down while selectively extracting butanol in the extract supplied from S9 at the middle gas-liquid contact part 2b.
  • the liquid extraction solvent is vaporized in the lower gas-liquid contact portion 2 c and moves to above the distillation column 2.
  • the remaining butanol flows down below the distillation column 2, is added to the liquid phase component described above, and is taken out from the bottom of the distillation column 2 to S16.
  • butanol substantially free from the extraction solvent and moisture can be taken out from the bottom of the distillation column 2 to S16.
  • the vapor-liquid equilibrium of the butanol / water system shows that butanol can be concentrated and dehydrated in the liquid phase when the liquid butanol concentration is 80 wt% or more. It can be easily dehydrated due to a synergistic effect with the liquid equilibrium characteristics.
  • the mixed vapor of extraction solvent and water substantially free of butanol is taken out to S11, compressed by the compressor 4, supplied to the intermediate heater 9 via S18, and the condensation latent heat
  • the latent heat of the steam is recovered by heating the intermediate retentate.
  • the intermediate holding liquid is a liquid that has been collected in the liquid intermediate holding unit 2d and taken out in S12.
  • the temperature of the liquid intermediate holding part 2d is higher than the temperature at the top of the distillation column 2 by 3 to 20 ° C., preferably 5 to 10 ° C.
  • the heating amount in the intermediate heater 9 for heating the intermediate retentate is adjusted. As a result, the power of the compressor 4 and the heat load of the reboiler 10 can be minimized.
  • the steam supplied to the intermediate heater 9 as described above is condensed and liquefied in the intermediate heater 9 and supplied to the water separation tank 3 via S19.
  • the specific gravity of the extraction solvent is about 0.6 to 0.8, which is lighter than water, so that it is easily separated into water and the extraction solvent by gravity sedimentation separation.
  • the separated water is taken out from the lower part of the water separation tank 3 to S20, and the extraction solvent is taken out from the upper part of the water separation tank 3 to S21.
  • a part of the extracted water is refluxed from S25 to the top of the distillation column 2. Thereby, the distillation purification effect can be enhanced.
  • the extraction solvent taken out to S21 from the upper part of the water separation tank 3 is supplied to S10 and S4 and reused.
  • butanol can be obtained which is substantially free of extraction solvent and moisture with low concentrated dehydration heat energy.
  • the concentrated dehydration heat energy is further reduced.
  • the energy per unit weight of butanol hardly changes regardless of the butanol concentration in the biobutanol aqueous solution. Therefore, when the butanol concentration in the biobutanol aqueous solution is high, the energy per unit weight of butanol is higher than the method of the present disclosure.
  • the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of a permeable membrane, so that problems relating to the permeable membrane are unlikely to occur.
  • the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of 2 octanol, and therefore a step of extracting and separating 2 octanol with a harmless solvent is not essential.
  • the butanol aqueous solution may be a fermented butanol (biobutanol) aqueous solution.
  • the butanol aqueous solution may contain acetone, ethanol, or both.
  • the purified product obtained by the present disclosure may be a mixed solution containing butanol and other components (for example, acetone, ethanol, or both).

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Abstract

A method for concentrating and dehydrating butanol according to one aspect of the present invention comprises: an extraction step for bringing a butanol aqueous solution into contact with an extraction solvent that is one or more substances selected from the group consisting of butane, isopentane, and n-pentane at an extraction temperature T and an extraction pressure P, and removing an extract containing the extraction solvent and extracted butanol; and a separation step for separating said extract, by distillation, into a gas-phase component containing butanol, water, and the extraction solvent and a liquid-phase component containing butanol, extracting the butanol contained in the gas-phase component using the liquid extraction solvent, adding the extracted butanol to the liquid-phase component, and removing the liquid-phase component. The extraction temperature T is within the range of 100-250°C and is 0.95 Tc or less, where Tc indicates the critical temperature of the extraction solvent. The extraction pressure P is greater than or equal to the vapor pressure of the extraction solvent at the extraction temperature T.

Description

ブタノールの濃縮脱水方法Concentrated dehydration method of butanol 関連出願の相互参照Cross-reference of related applications
　本国際出願は、２０１４年１１月２０日に日本国特許庁に出願された日本国特許出願第２０１４－２３５４９５号に基づく優先権を主張するものであり、日本国特許出願第２０１４－２３５４９５号の全内容を本国際出願に参照により援用する。 This international application claims priority based on Japanese Patent Application No. 2014-235495 filed with the Japan Patent Office on November 20, 2014, and is based on Japanese Patent Application No. 2014-235495. The entire contents are incorporated by reference into this international application.
本開示は、ブタノールの濃縮脱水方法に関する。 The present disclosure relates to a method for concentrating and dehydrating butanol.
　バイオブタノールはバイオエタノール比べて、発熱量大、吸湿性小、ガソリン蒸気圧増加作用無、ガソリン及び軽油に添加可能であること等、自動車燃料として優れた性状を有する。また、Ｃ５糖のエタノール発酵では遺伝子組換酵母が必要であるが、ブタノール発酵では既存酵母を使用可能である等多くの長所があり、ポストエタノールとして注目されている。
　しかし、サトウキビ、トウモロコシ、草、木等のバイオマスを糖化発酵して製造されるバイオブタノールの濃度は、ブタノールの強い発酵阻害のため、０．５～１．０ｗｔ％と希薄であり、残りは水分である。 Compared with bioethanol, biobutanol has excellent properties as an automobile fuel, such as high calorific value, low hygroscopicity, no effect on gasoline vapor pressure increase, and addition to gasoline and light oil. In addition, genetically modified yeast is required for ethanol fermentation of C5 sugar, but there are many advantages such as the ability to use existing yeast in butanol fermentation, and it has attracted attention as post-ethanol.
However, the concentration of biobutanol produced by saccharification and fermentation of biomass such as sugarcane, corn, grass, and wood is dilute at 0.5 to 1.0 wt% due to strong fermentation inhibition of butanol, and the rest is moisture. It is.
　バイオブタノールは、ノルマルブタノールまたはイソブタノールを主成分とする水溶液であり、よく知られているＡＢＥ発酵では、ノルマルブタノール約１．０ｗｔ％、アセトン約０．６ｗｔ％、エタノール約０．１ｗｔ％の濃度の水溶液が得られる。近年、遺伝子組み換えにより、ブタノール発酵阻害に耐性を持たせた酵母が開発され、バイオブタノールにおけるブタノール濃度を向上させることが行われており、約２．０～３．０ｗｔ％程度のブタノール発酵濃度が実現可能である。 Biobutanol is an aqueous solution mainly composed of normal butanol or isobutanol. In the well-known ABE fermentation, the concentration of normal butanol is about 1.0 wt%, acetone is about 0.6 wt%, and ethanol is about 0.1 wt%. An aqueous solution of In recent years, yeast having resistance to butanol fermentation inhibition has been developed by genetic recombination, and the butanol concentration in biobutanol has been improved, and a butanol fermentation concentration of about 2.0 to 3.0 wt% has been achieved. It is feasible.
　バオブタノールの主な用途であるガソリン添加剤として使用するには、バオブタノールを濃縮・脱水して水分濃度０．１ｗｔ％以下の無水ブタノールにする必要がある。バイオブタノールはカーボンニュートラルであるため、二酸化炭素削減に寄与するが、その製造エネルギーが少ないほどその効果は大きくなる。しかし、従来の蒸留濃縮脱水法は、バイブタノール発熱量３４ＭＪ／ｋｇと同等の大量のエネルギーが必要であり、その削減が急務の課題である。 To use as a gasoline additive, which is the main application of Baobutanol, it is necessary to concentrate and dehydrate Baobutanol to make anhydrous butanol having a water concentration of 0.1 wt% or less. Since biobutanol is carbon neutral, it contributes to the reduction of carbon dioxide, but the effect increases as the production energy decreases. However, the conventional distillation concentration dehydration method requires a large amount of energy equivalent to the bibutanol calorific value of 34 MJ / kg, and its reduction is an urgent issue.
　ブタノールの濃縮脱水方法として、以下の方法が提案されている。
　（１）濃度約１．０ｗｔ％の希薄ブタノール水溶液から、ブタノール透過膜で濃度約８０ｗｔ％の濃縮ブタノールを回収し、その８０ｗｔ％濃縮ブタノール液から、水透過膜で水分を分離して無水ブタノールを分離回収する方法（特許文献１参照）。 The following methods have been proposed as a method for concentrating and dehydrating butanol.
(1) From a diluted butanol aqueous solution having a concentration of about 1.0 wt%, concentrated butanol having a concentration of about 80 wt% is recovered with a butanol permeable membrane. Separation and recovery method (see Patent Document 1).
　（２）ブタノールの溶解度と選択性の高い２オクタノールを常温で液体溶媒として用いる溶媒抽出法。 (2) Solvent extraction method using 2-octanol, which has high butanol solubility and selectivity, as a liquid solvent at room temperature.
特許第５５７８５６５号公報Japanese Patent No. 5578565
　上記（１）の方法に要するエネルギーは約５ＭＪ／ｋｇと少ないが、実用化のためには、膜の透過速度向上、膜劣化や不純物による膜内部および表面への汚れ付着の課題を解決する必要があると考えられる。また、上記（２）の方法に要するエネルギーも約５ＭＪ／ｋｇと少ないが、２オクタノールは酵母に対する毒性が大きく、水に溶解した２オクタノールを無害な溶媒で抽出分離しなければならず、抽出塔２基と蒸留塔２基とを備えた複雑なシステムが必要となる。 The energy required for the method (1) is as low as about 5 MJ / kg. However, for practical use, it is necessary to solve the problems of improving the permeation rate of the film, film deterioration, and contamination of the film due to impurities inside and on the surface. It is thought that there is. Further, the energy required for the method (2) is as low as about 5 MJ / kg, but 2 octanol is highly toxic to yeast, and 2 octanol dissolved in water must be extracted and separated with a harmless solvent. A complex system with two units and two distillation columns is required.
　本開示の一局面は新規なブタノールの濃縮脱水方法を提供することである。 One aspect of the present disclosure is to provide a novel butanol concentration and dehydration method.
　本開示の一局面のブタノールの濃縮脱水方法は、ブタノール水溶液と、ブタン、イソペンタン、及びノルマルペンタンから成る群から選択される１種以上である抽出溶媒とを、抽出温度Ｔ及び抽出圧力Ｐの条件下で接触させ、前記抽出溶媒、及び抽出されたブタノールを含む抽出物を取り出す抽出工程と、前記抽出物を、蒸留により、ブタノール、水、及び前記抽出溶媒を含む気相成分と、ブタノールを含む液相成分とに分離するとともに、前記気相成分に含まれるブタノールを液状の前記抽出溶媒により抽出し、抽出されたブタノールを前記液相成分に加え、前記液相成分を取り出す分離工程と、を備える。前記抽出温度Ｔは、１００～２５０℃の範囲内であり、且つ前記抽出溶媒の臨界温度をＴｃとしたとき、前記抽出温度Ｔは０．９５Ｔｃ以下であり、前記抽出圧力Ｐは、前記抽出温度Ｔにおける前記抽出溶媒の蒸気圧以上である。 According to one aspect of the present disclosure, a method for concentrating and dehydrating butanol includes an aqueous butanol solution and an extraction solvent selected from the group consisting of butane, isopentane, and normal pentane under conditions of an extraction temperature T and an extraction pressure P. An extraction step of bringing the extraction solvent and the extracted butanol-containing extract into contact with each other; and extracting the extract by distillation, butanol, water, and a gas phase component containing the extraction solvent, and butanol Separating into a liquid phase component, extracting butanol contained in the gas phase component with the liquid extraction solvent, adding the extracted butanol to the liquid phase component, and taking out the liquid phase component; Prepare. The extraction temperature T is in the range of 100 to 250 ° C., and when the critical temperature of the extraction solvent is Tc, the extraction temperature T is 0.95 Tc or less, and the extraction pressure P is the extraction temperature P It is equal to or higher than the vapor pressure of the extraction solvent at T.
　本開示のブタノールの濃縮脱水方法は、ブタノールの濃縮脱水に要するエネルギーを低減できる。また、本開示のブタノールの濃縮脱水方法は、必ずしも透過膜を使用しなくてもよいので、透過膜に関する問題が生じにくい。また、本開示のブタノールの濃縮脱水方法は、必ずしも２オクタノールを使用しなくてもよいので、２オクタノールを無害な溶媒で抽出分離する工程が必須ではない。 The method of concentrating and dehydrating butanol according to the present disclosure can reduce the energy required for concentrating and dehydrating butanol. Further, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of a permeable membrane. In addition, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of 2 octanol, and therefore a step of extracting and separating 2 octanol with a harmless solvent is not essential.
図１は、炭素数１から１０までのパラフィン系炭化水素と炭素数６から８の環式炭化水素化合物の主要物性を表す表である。FIG. 1 is a table showing the main physical properties of paraffinic hydrocarbons having 1 to 10 carbon atoms and cyclic hydrocarbon compounds having 6 to 8 carbon atoms. 図２は、温度とブタノール選択性との関係を表すグラフである。FIG. 2 is a graph showing the relationship between temperature and butanol selectivity. 図３は、温度とブタノール溶解度との関係を表すグラフである。FIG. 3 is a graph showing the relationship between temperature and butanol solubility. 図４は、ブタノールの濃縮脱水方法に使用する装置の構成を表す説明図である。FIG. 4 is an explanatory diagram showing the configuration of an apparatus used for the butanol concentration and dehydration method. 図５は、ノルマルブタノール（ＮＢＡ）／水系の気液平衡線図である。FIG. 5 is a vapor-liquid equilibrium diagram of normal butanol (NBA) / water system. 図６は、ブタノールの濃縮脱水方法の実験条件と、実験結果とを表す表である。FIG. 6 is a table showing experimental conditions and experimental results of the butanol concentration and dehydration method. 図７は、ブタノール水溶液におけるブタノール濃度と、濃縮脱水熱エネルギーとの関係を表すグラフである。FIG. 7 is a graph showing the relationship between the butanol concentration in the butanol aqueous solution and the concentrated dehydration heat energy.
１…抽出塔、１ａ…気液接触部、２…蒸留塔、２ａ…上層気液接触部、２ｂ…中層気液接触部、２ｃ…下層気液接触部、２ｄ…液中間保持部、３…水分離槽、４…圧縮機、５、６、７、８、１１…熱交換器、９…中間加熱器、１０…リボイラー、１２、１３、１４…圧力制御装置、１００…装置 DESCRIPTION OF SYMBOLS 1 ... Extraction tower, 1a ... Gas-liquid contact part, 2 ... Distillation tower, 2a ... Upper gas-liquid contact part, 2b ... Middle gas-liquid contact part, 2c ... Lower gas-liquid contact part, 2d ... Liquid intermediate holding part, 3 ... Water separation tank, 4 ... compressor, 5, 6, 7, 8, 11 ... heat exchanger, 9 ... intermediate heater, 10 ... reboiler, 12, 13, 14 ... pressure control device, 100 ... device
　本開示の実施形態を説明する。本開示で用いるブタノール水溶液は、水以外の成分としてノルマルブタノールまたはイソブタノールを主成分とする水溶液であり、ノルマルブタノールまたはイソブタノールが１～８０％、水が９９～２０％含まれ、好ましくは、ノルマルブタノールまたはイソブタノールが１～３％、水が９９～７％含まれる。通常、発酵法で得られるバイオブタノールを対象とするが、合成化学反応工程や洗浄工程等から回収されて得られるブタノール水溶液であってもよい。バイオブタノールとしては、ＡＢＥ発酵（Ａｃｅｔｏｎｅ－ｂｕｔａｎｏｌ－ｅｔｈａｎｏｌ　（ＡＢＥ）　ｆｅｒｍｅｎｔａｔｉｏｎ：デンプンからアセトン、ノルマルブタノール、エタノールを合成する。）遺伝子組み換え酵母による発酵から得られるブタノール水溶液であってもよい。また、バイオエタノールから触媒合成反応で得られるブタノール水溶液であってもよい。本開示で用いる抽出溶媒は、疎水性でブタノールの溶解度が高く、ブタノールの選択性が高く、高濃度のブタノールを抽出できるものが好ましい。更には、抽出工程の後に排出される抽出排水をバイオブタノールの発酵工程に循環使用する場合は、抽出溶媒は毒性のないものが好ましい。また、抽出溶媒の損失防止のため、抽出溶媒は抽出排水（例えば水）に溶解しないものが好ましい。更には、ブタノールと共沸を形成せず、且つブタノールより沸点の低い抽出溶媒が好ましい。共沸を形成すると、抽出溶媒にブタノールが同伴してブタノールの損失が増加する。また、ブタノールより沸点が高いと、抽出溶媒とブタノールとの分離が困難となる。 An embodiment of the present disclosure will be described. The butanol aqueous solution used in the present disclosure is an aqueous solution mainly containing normal butanol or isobutanol as a component other than water, and contains 1 to 80% normal butanol or isobutanol, and 99 to 20% water, preferably, It contains 1 to 3% normal butanol or isobutanol and 99 to 7% water. Usually, biobutanol obtained by fermentation is targeted, but an aqueous solution of butanol obtained by recovery from a synthetic chemical reaction step, a washing step, or the like may be used. The biobutanol may be an aqueous solution of butanol obtained from fermentation by ABE fermentation (acetone-butanol-ethanol (ABE) fermentation: synthesizing acetone, normal butanol, ethanol from starch) genetically modified yeast. Moreover, the butanol aqueous solution obtained by a catalyst synthesis reaction from bioethanol may be sufficient. The extraction solvent used in the present disclosure is preferably a hydrophobic solvent having high butanol solubility, high butanol selectivity, and capable of extracting a high concentration of butanol. Furthermore, when the extracted waste water discharged after the extraction step is recycled for use in the biobutanol fermentation step, the extraction solvent is preferably non-toxic. In order to prevent the loss of the extraction solvent, it is preferable that the extraction solvent does not dissolve in the extraction waste water (for example, water). Furthermore, an extraction solvent that does not form an azeotrope with butanol and has a lower boiling point than butanol is preferred. When azeotrope is formed, butanol is entrained in the extraction solvent and the loss of butanol increases. Further, when the boiling point is higher than that of butanol, it becomes difficult to separate the extraction solvent and butanol.
　本開示の発明者は、これらの条件に適合して水に殆ど溶解せず、酵母に対する毒性の低いパラフィン系炭化水素に注目した。従来、パラフィン系炭化水素はブタノールの溶解度が低く、抽出溶媒としては不適とされてきた。 The inventors of the present disclosure have focused on paraffinic hydrocarbons that meet these conditions and hardly dissolve in water and have low toxicity to yeast. Conventionally, paraffinic hydrocarbons have low butanol solubility and have been made unsuitable as extraction solvents.
　しかし、本開示の発明者は、ブタノールの温度を上げるとその蒸気圧が増大し、特に、ブタノールの沸点（イソブタノールの沸点：３８１Ｋ、ノルマルブタノールの沸点：３９０．９Ｋ）近傍では温度上昇ともに指数的に蒸気圧が増大して、抽出溶媒へのブタノールの溶解度が急激に増加することを見出した。 However, the inventor of the present disclosure increases the vapor pressure when the temperature of butanol is increased. Particularly, in the vicinity of the boiling point of butanol (boiling point of isobutanol: 381K, boiling point of normal butanol: 390.9K), the temperature increases as an index. In particular, it was found that the solubility of butanol in the extraction solvent increases rapidly as the vapor pressure increases.
　また、ブタノールは疎水性が強いので、抽出溶媒は疎水性かつ密度が大きいほど、ブタノールとの分子間引力が大きくなり、溶解度と選択性が増加する。パラフィン系炭化水素は疎水性で、その密度は臨界温度に近づくと急激に減少するので、臨界温度がブタノールの沸点近傍である約１００℃よりも大きいパラフィン系炭化水素を抽出溶媒とすることが好ましい。 In addition, since butanol is highly hydrophobic, as the extraction solvent becomes more hydrophobic and dense, the intermolecular attractive force with butanol increases and the solubility and selectivity increase. Paraffinic hydrocarbons are hydrophobic, and their density rapidly decreases as they approach the critical temperature. Therefore, it is preferable to use paraffinic hydrocarbons whose critical temperature is higher than about 100 ° C. near the boiling point of butanol as the extraction solvent. .
　図１に炭素数１から１０までのパラフィン系炭化水素と炭素数６から８の環式炭化水素化合物の主要物性を示す。このなかで、メタン、エタン、プロパンの臨界温度はブタノールの沸点より低く、抽出溶媒として好ましくない。 Fig. 1 shows the main physical properties of paraffinic hydrocarbons having 1 to 10 carbon atoms and cyclic hydrocarbon compounds having 6 to 8 carbon atoms. Among these, the critical temperature of methane, ethane, and propane is lower than the boiling point of butanol, which is not preferable as an extraction solvent.
　環式炭化水素はブタノールとの共沸を形成するため好ましくない。Ｃ８（炭素数８）以上のパラフィン炭化水素は沸点がブタノールより高いので好ましくない。ベンゼンは発がん性があるため、好ましくない。　　Ｃ７、Ｃ８のパラフィン炭化水素はブタノールと無視できない共沸を形成するので好ましくない。ブタン、イソペンタン、ノルマルペンタン又はこれらの混合物が抽出溶媒として全ての条件に適合して好ましいことを見出した。よって、抽出溶媒は、ブタン、イソペンタン、及びノルマルペンタンから成る群から選択される１種以上である。 Cyclic hydrocarbons are not preferred because they form an azeotrope with butanol. Paraffin hydrocarbons having C8 (carbon number 8) or higher are not preferable because their boiling points are higher than butanol. Benzene is not preferred because it is carcinogenic. C7 and C8 paraffin hydrocarbons are not preferable because they form a non-negligible azeotrope with butanol. We have found that butane, isopentane, normal pentane or mixtures thereof are preferred as the extraction solvent in conformity with all conditions. Therefore, the extraction solvent is at least one selected from the group consisting of butane, isopentane, and normal pentane.
　一方、抽出温度Ｔは、基本的には、高いほど好ましいが、抽出温度Ｔが約２５０℃を超えると濃縮ブタノール濃度の低下とブタノールの熱分解反応が進行するので、２５０℃以下にすべきである。更には、抽出溶媒の密度を高く保持する観点から、対臨界温度ＴＲ（抽出温度Ｔ／抽出溶媒の臨界温度Ｔｃ：温度は絶対温度Ｋ）を０．９５以下にし、抽出圧力Ｐは抽出溶媒の抽出温度Ｔにおける蒸気圧以上にすることが望ましい。すなわち、抽出温度Ｔは０．９５Ｔｃ以下である。抽出溶媒の蒸気圧以上では抽出溶媒の密度の圧力依存性は低く、高圧化による溶解度の増加や選択性の向上効果は小さいこと、及び抽出塔の圧力は圧力制御弁の作動により±０．１～０．２ＭＰａ程度変動することから、抽出圧力Ｐは抽出温度における抽出溶媒の蒸気圧の１．１倍以上１．２倍以下にして、蒸気圧以下に絶対にならないようにすることが好ましい。これ以上の高圧は装置肉厚の増大による設備コスト増加およびポンプ動力増加による運転コスト増加のデメリットが優勢となり好ましくない。 On the other hand, the extraction temperature T is basically preferably as high as possible. However, if the extraction temperature T exceeds about 250 ° C., the concentration of concentrated butanol decreases and the thermal decomposition reaction of butanol proceeds. is there. Furthermore, from the viewpoint of keeping the density of the extraction solvent high, the critical temperature TR (extraction temperature T / extraction solvent critical temperature Tc: temperature is absolute temperature K) is set to 0.95 or less, and the extraction pressure P is set to It is desirable that the vapor pressure be equal to or higher than the extraction temperature T. That is, the extraction temperature T is 0.95 Tc or less. Above the vapor pressure of the extraction solvent, the pressure dependence of the density of the extraction solvent is low, the effect of increasing the solubility and selectivity by increasing the pressure is small, and the pressure of the extraction tower is ± 0.1 by the operation of the pressure control valve. Since it fluctuates by about ~ 0.2 MPa, it is preferable that the extraction pressure P be 1.1 times or more and 1.2 times or less the vapor pressure of the extraction solvent at the extraction temperature so that it never becomes less than the vapor pressure. Higher pressure than this is not preferable because the disadvantage of increased equipment cost due to increased apparatus thickness and increased operating cost due to increased pump power is dominant.
　以上のとおり、ブタン、イソペンタン、ノルマルペンタン又はこれらの混合物からなる抽出溶媒を用いて、抽出温度Ｔは、１００～２５０℃の範囲内であり、且つ前記抽出温度Ｔは０．９５Ｔｃ以下であり、抽出圧力Ｐは抽出温度Ｔにおける抽出溶媒の蒸気圧以上、蒸気圧の１．２倍以下であるという条件下で、ブタノール水溶液と抽出溶媒とを接触（例えば向流接触）させることにより、ブタノールの溶解度と選択性を向上できることを見出した。 As described above, using an extraction solvent composed of butane, isopentane, normal pentane, or a mixture thereof, the extraction temperature T is in the range of 100 to 250 ° C., and the extraction temperature T is 0.95 Tc or less. The extraction pressure P is not less than the vapor pressure of the extraction solvent at the extraction temperature T and not more than 1.2 times the vapor pressure. By contacting the butanol aqueous solution with the extraction solvent (for example, countercurrent contact), It has been found that solubility and selectivity can be improved.
　抽出圧力Ｐは４ＭＰａ、抽出温度Ｔは４０～１７０℃の条件下で、ノルマルブタノール濃度１．０ｗｔ％水溶液（平衡時におけるノルマルブタノール濃度が１．０ｗｔ％である水溶液）にブタン溶媒（抽出溶媒の一例）を添加して抽出工程を行い、抽出後におけるブタン溶媒中のブタノール濃度及び水分濃度を分析した。ブタノール選択性（ブタノール濃縮濃度）の測定結果を図２に示し、ブタノール溶解度の測定結果を図３に示す。なお、ブタノール選択性は、気相に含まれるブタノールと水との全量を１００としたとき、気相に含まれるブタノールの量（すなわち、溶媒フリーでのブタノール濃度）である。また、ブタノール溶解度は、気相におけるブタノールの濃度である。 The extraction pressure P is 4 MPa, the extraction temperature T is 40 to 170 ° C., a normal butanol concentration of 1.0 wt% aqueous solution (an aqueous solution having a normal butanol concentration of 1.0 wt% at equilibrium) and a butane solvent (extraction solvent concentration). An example) was added to perform the extraction step, and the butanol concentration and water concentration in the butane solvent after extraction were analyzed. The measurement result of butanol selectivity (butanol concentration) is shown in FIG. 2, and the measurement result of butanol solubility is shown in FIG. The butanol selectivity is the amount of butanol contained in the gas phase (that is, the solvent-free butanol concentration) when the total amount of butanol and water contained in the gas phase is 100. Butanol solubility is the concentration of butanol in the gas phase.
　図２、図３に示す結果から、ブタノール選択性とブタノール溶解度の両方を同時に大きくできる好ましい抽出温度Ｔは、１１０～１３０℃であることがわかる。また、ブタノール選択性とブタノール溶解度の両方を同時に大きくできる抽出溶媒の対臨界温度ＴＲは、０．９０～０．９４８の範囲である。 2 and 3 show that a preferable extraction temperature T that can simultaneously increase both the butanol selectivity and the butanol solubility is 110 to 130 ° C. The critical temperature TR of the extraction solvent that can simultaneously increase both the butanol selectivity and the butanol solubility is in the range of 0.90 to 0.948.
　なお、１１０℃での対臨界温度ＴＲは、（１１０＋２７３）／（１５２＋２７３）＝０．９０である。また、１３０℃での対臨界温度ＴＲは、（１３０＋２７３）／（１５２＋２７３）＝０．９４８である。
（実施例１）
　１．ブタノールの濃縮脱水方法に使用する装置１００の構成、ブタノールの濃縮脱水方法に使用する装置１００の構成を図４に基づき説明する。 The critical temperature TR at 110 ° C. is (110 + 273) / (152 + 273) = 0.90. Further, the critical temperature TR at 130 ° C. is (130 + 273) / (152 + 273) = 0.948.
(Example 1)
1. The configuration of the apparatus 100 used for the butanol concentration and dehydration method and the configuration of the apparatus 100 used for the butanol concentration and dehydration method will be described with reference to FIG.
　装置１００は、抽出塔１と、蒸留塔２と、水分離槽３と、圧縮機４と、熱交換器５、６、７、８、１１と、中間加熱器９と、リボイラー１０と、圧力制御装置１２、１３、１４と、を備える。また、装置１００の各部位は、配管により接続されており、その配管を経由して物質の移送が可能である。図１におけるＳ１～Ｓ２４は、配管を経由した物質の移送を表すストリーム番号である。 The apparatus 100 includes an extraction tower 1, a distillation tower 2, a water separation tank 3, a compressor 4, heat exchangers 5, 6, 7, 8, 11, an intermediate heater 9, a reboiler 10, a pressure And control devices 12, 13, and 14. Moreover, each part of the apparatus 100 is connected by piping, and a substance can be transferred via the piping. In FIG. 1, S1 to S24 are stream numbers representing the transfer of substances via pipes.
　抽出塔１は、縦型円筒容器であり、その内部に気液接触部１ａを備える。気液接触部１ａとしては、気液の接触効率を増大させるために一般に使用される棚段、不規則充填物、規則充填物等を用いることができる。 The extraction tower 1 is a vertical cylindrical container, and includes a gas-liquid contact portion 1a therein. As the gas-liquid contact portion 1a, a shelf, an irregular packing, a regular packing, or the like generally used for increasing the gas-liquid contact efficiency can be used.
　蒸留塔２は、縦型円筒容器であり、その内部に上層気液接触部２ａ、中層気液接触部２ｂ、及び下層気液接触部２ｃを備える。上層気液接触部２ａ、中層気液接触部２ｂ、及び下層気液接触部２ｃの構成は、それぞれ、気液接触部１ａと同様である。 The distillation tower 2 is a vertical cylindrical container, and includes an upper gas-liquid contact part 2a, an intermediate gas-liquid contact part 2b, and a lower gas-liquid contact part 2c. The configurations of the upper-layer gas-liquid contact portion 2a, the middle-layer gas-liquid contact portion 2b, and the lower-layer gas-liquid contact portion 2c are the same as those of the gas-liquid contact portion 1a.
　蒸留塔２の内部のうち、中層気液接触部２ｂと下層気液接触部２ｃとの間に、液中間保持部２ｄが存在する。液中間保持部２ｄは、上方から流下した液体を一定量まで保持する。液中間保持部２ｄに保持された液量が一定量を超えると、液体はオーバーフローし、液中間保持部２ｄよりも下方に流下する。 In the inside of the distillation column 2, a liquid intermediate holding part 2d exists between the middle gas-liquid contact part 2b and the lower gas-liquid contact part 2c. The liquid intermediate holding part 2d holds the liquid flowing down from above up to a certain amount. When the amount of liquid held in the liquid intermediate holding part 2d exceeds a certain amount, the liquid overflows and flows down below the liquid intermediate holding part 2d.
　抽出塔１及び蒸留塔２内の温度は、図示しない温調機構により制御される。また、抽出塔１、蒸留塔２、及び水分離槽３内の圧力は、圧力制御装置１２、１４、１３によりそれぞれ制御される。 The temperature in the extraction tower 1 and the distillation tower 2 is controlled by a temperature control mechanism (not shown). Moreover, the pressure in the extraction tower 1, the distillation tower 2, and the water separation tank 3 is controlled by the pressure control devices 12, 14, and 13, respectively.
　２．ブタノールの濃縮脱水方法
　（２－１）抽出工程
　バイオブタノール水溶液（濃度：約０．５～２．０ｗｔ％）を熱交換器５、６で予熱後に、Ｓ３から抽出塔１の上部に供給する。また、抽出溶媒を、熱交換器８、７で予熱後に、Ｓ４から抽出塔１の下部に供給する。 2. (2-1) Extraction Step After preheating the biobutanol aqueous solution (concentration: about 0.5 to 2.0 wt%) with the heat exchangers 5 and 6, the solution is supplied from S3 to the upper part of the extraction tower 1. The extraction solvent is supplied to the lower part of the extraction tower 1 from S4 after preheating in the heat exchangers 8 and 7.
　このとき、抽出塔１内の温度（以下、抽出温度Ｔとする）と、抽出塔１内の圧力（以下、抽出圧力Ｐとする）は、以下の条件を満たすものとする。
　抽出温度Ｔ：１００～２５０℃の範囲内であり、且つ０．９５Ｔｃ以下である。ここで、Ｔｃは、抽出溶媒の臨界温度である。 At this time, the temperature in the extraction tower 1 (hereinafter referred to as extraction temperature T) and the pressure in the extraction tower 1 (hereinafter referred to as extraction pressure P) shall satisfy the following conditions.
Extraction temperature T: within a range of 100 to 250 ° C. and 0.95 Tc or less. Here, Tc is the critical temperature of the extraction solvent.
　抽出圧力Ｐ：抽出温度Ｔにおける抽出溶媒の蒸気圧以上であること。
抽出塔１の上部から流下するバイオブタノール水溶液と、抽出塔１の下部から上昇する抽出溶媒とは向流接触し、バイオブタノール水溶液中のブタノールは、抽出溶媒中に抽出される。抽出塔１の上部からＳ６に、抽出されたブタノールと抽出溶媒とを含む抽出物を取り出す。また、抽出塔１の底部からＳ５に、水を取り出す。この水にはブタノールと抽出溶媒とは実質的に含まれない。 Extraction pressure P: Being equal to or higher than the vapor pressure of the extraction solvent at the extraction temperature T.
The biobutanol aqueous solution flowing down from the upper part of the extraction tower 1 and the extraction solvent rising from the lower part of the extraction tower 1 are in countercurrent contact, and the butanol in the biobutanol aqueous solution is extracted into the extraction solvent. An extract containing the extracted butanol and the extraction solvent is taken out from the upper part of the extraction tower 1 to S6. Moreover, water is taken out from the bottom of the extraction tower 1 to S5. This water is substantially free of butanol and extraction solvent.
　（２－２）分離工程
　抽出塔１の上部から取り出した抽出物を、熱交換器８、１１を経由してＳ９から蒸留塔２に供給する。抽出物は、蒸留塔２内で、ブタノール、水、及び抽出溶媒を含む気相成分と、ブタノールを含む液相成分とに分離する。ブタノールを含む液相成分は蒸留塔２の下方に流下し、蒸留塔２の底部からＳ１６に取り出される。 (2-2) Separation Step The extract taken from the upper part of the extraction tower 1 is supplied from S9 to the distillation tower 2 via the heat exchangers 8 and 11. The extract is separated in the distillation column 2 into a gas phase component containing butanol, water, and an extraction solvent, and a liquid phase component containing butanol. The liquid phase component containing butanol flows down below the distillation column 2 and is taken out from the bottom of the distillation column 2 to S16.
　また、Ｓ１０から液状の抽出溶媒を蒸留塔２に供給する。液状の抽出溶媒は上層気液接触部２ａで気相中のブタノールを吸収しながら流下し、中層気液接触部２ｂではＳ９から供給された抽出物中のブタノールを選択的に抽出しながら流下して液中間保持部２ｄに至る。液状の抽出溶媒と抽出されたブタノールのうち、液状の抽出溶媒は下層気液接触部２ｃにおいて気化し、蒸留塔２の上方に移動する。残ったブタノールは、蒸留塔２の下方に流下し、上述した液相成分に加わり、蒸留塔２の底部からＳ１６に取り出される。 Also, a liquid extraction solvent is supplied to the distillation tower 2 from S10. The liquid extraction solvent flows down while absorbing butanol in the gas phase at the upper gas-liquid contact part 2a, and flows down while selectively extracting butanol in the extract supplied from S9 at the middle gas-liquid contact part 2b. To the liquid intermediate holding part 2d. Of the liquid extraction solvent and the extracted butanol, the liquid extraction solvent is vaporized in the lower gas-liquid contact portion 2 c and moves to above the distillation column 2. The remaining butanol flows down below the distillation column 2, is added to the liquid phase component described above, and is taken out from the bottom of the distillation column 2 to S16.
　以上のようにして、蒸留塔２の底部からＳ１６に、実質的に抽出溶媒と水分とを含まないブタノールを取り出すことができる。
　なお、図５に示すように、ブタノール／水系の気液平衡は、液相ブタノール濃度が８０ｗｔ％以上で液相にブタノールが濃縮され無水化できることを示しており、抽出溶媒のブタノール抽出特性と気液平衡特性との相乗効果により容易に無水化できる。 As described above, butanol substantially free from the extraction solvent and moisture can be taken out from the bottom of the distillation column 2 to S16.
As shown in FIG. 5, the vapor-liquid equilibrium of the butanol / water system shows that butanol can be concentrated and dehydrated in the liquid phase when the liquid butanol concentration is 80 wt% or more. It can be easily dehydrated due to a synergistic effect with the liquid equilibrium characteristics.
　蒸留塔２の塔頂からＳ１１に、実質的にブタノールを含まない抽出溶媒と水の混合蒸気を取り出し、圧縮機４で圧縮し、Ｓ１８を介して中間加熱器９に供給し、その凝縮潜熱で中間保持液を加熱することにより、蒸気の潜熱を回収する。ここで、中間保持液とは、液中間保持部２ｄに溜まった液を、Ｓ１２に取り出したものである。液中間保持部２ｄの温度が、蒸留塔２の塔頂の温度より３～２０℃、好ましくは５～１０℃の範囲で高くなるように、
中間保持液を加熱する中間加熱器９での加熱量を調整する。このことにより、圧縮機４の動力とリボイラー１０の熱負荷を最少にできる。 From the top of the distillation column 2, the mixed vapor of extraction solvent and water substantially free of butanol is taken out to S11, compressed by the compressor 4, supplied to the intermediate heater 9 via S18, and the condensation latent heat The latent heat of the steam is recovered by heating the intermediate retentate. Here, the intermediate holding liquid is a liquid that has been collected in the liquid intermediate holding unit 2d and taken out in S12. The temperature of the liquid intermediate holding part 2d is higher than the temperature at the top of the distillation column 2 by 3 to 20 ° C., preferably 5 to 10 ° C.
The heating amount in the intermediate heater 9 for heating the intermediate retentate is adjusted. As a result, the power of the compressor 4 and the heat load of the reboiler 10 can be minimized.
　上記のように中間加熱器９に供給された蒸気は、中間加熱器９において凝縮液化し、Ｓ１９を介して水分離槽３に供給される。水分離槽３に供給される液体のうち、抽出溶媒の比重は約０．６～０．８と水より軽いので、重力沈降分離により水と抽出溶媒とに容易に分離される。分離された水は、水分離槽３の下部からＳ２０に取り出され、抽出溶媒は水分離槽３の上部からＳ２１に取り出される。取り出された水の一部は、Ｓ２５から蒸留塔２の塔頂に還流する。このことにより、蒸留精製効果を高めることができる。また、水分離槽３の上部からＳ２１に取り出された抽出溶媒は、Ｓ１０及びＳ４に供給され、再利用される。 The steam supplied to the intermediate heater 9 as described above is condensed and liquefied in the intermediate heater 9 and supplied to the water separation tank 3 via S19. Among the liquids supplied to the water separation tank 3, the specific gravity of the extraction solvent is about 0.6 to 0.8, which is lighter than water, so that it is easily separated into water and the extraction solvent by gravity sedimentation separation. The separated water is taken out from the lower part of the water separation tank 3 to S20, and the extraction solvent is taken out from the upper part of the water separation tank 3 to S21. A part of the extracted water is refluxed from S25 to the top of the distillation column 2. Thereby, the distillation purification effect can be enhanced. Moreover, the extraction solvent taken out to S21 from the upper part of the water separation tank 3 is supplied to S10 and S4 and reused.
　３．実験
　上述したブタノールの濃縮脱水方法を、図６に示す条件で行った。そして、抽出塔１の上部から取り出した抽出物について、抽出溶媒中のブタノール溶解度と、抽出溶媒中のブタノール濃度とを測定した。その結果を図６に示す。 3. Experiment The above-described method for concentrating and dehydrating butanol was performed under the conditions shown in FIG. And about the extract taken out from the upper part of the extraction tower 1, the butanol solubility in an extraction solvent and the butanol density | concentration in an extraction solvent were measured. The result is shown in FIG.
　また、図６に示す各条件について、バイオブタノール水溶液から、実質的に抽出溶媒と水分とを含まないブタノールを得るために必要なエネルギーである、濃縮脱水熱エネルギーをシミュレーションにより算出した。その結果を図６及び図７に示す。 Further, for each condition shown in FIG. 6, concentrated dehydration heat energy, which is energy necessary for obtaining butanol substantially free from extraction solvent and moisture, from the aqueous biobutanol solution was calculated by simulation. The results are shown in FIGS.
　本開示によれば、低い濃縮脱水熱エネルギーで、実質的に抽出溶媒と水分とを含まないブタノールを得ることができる。特に、バイオブタノール水溶液におけるブタノール濃度が高い場合、濃縮脱水熱エネルギーが一層低くなる。 According to the present disclosure, butanol can be obtained which is substantially free of extraction solvent and moisture with low concentrated dehydration heat energy. In particular, when the butanol concentration in the aqueous biobutanol solution is high, the concentrated dehydration heat energy is further reduced.
　これは、本開示の濃縮脱水方法では、バイオブタノール水溶液におけるブタノール濃度が高くなっても、溶媒へのブタノール溶解度はブタノール濃度にほぼ比例して増加し、濃縮脱水熱エネルギーは増加しないので、バイオブタノール水溶液におけるブタノール濃度が高くなるほど、ブタノールの単位重量当りの濃縮脱水熱エネルギーは低くなるためである。 This is because, in the concentrated dehydration method of the present disclosure, even when the butanol concentration in the biobutanol aqueous solution increases, the butanol solubility in the solvent increases almost in proportion to the butanol concentration, and the concentrated dehydration heat energy does not increase. This is because the concentrated dehydration heat energy per unit weight of butanol decreases as the concentration of butanol in the aqueous solution increases.
　一方、従来の膜分離法では、その原理上、バイオブタノール水溶液におけるブタノール濃度によらず、ブタノールの単位重量当たりのエネルギーは殆ど変化しない。そのため、バイオブタノール水溶液におけるブタノール濃度が高い場合は、本開示の方法に比べ、ブタノールの単位重量当たりのエネルギーが高くなる。 On the other hand, in the conventional membrane separation method, the energy per unit weight of butanol hardly changes regardless of the butanol concentration in the biobutanol aqueous solution. Therefore, when the butanol concentration in the biobutanol aqueous solution is high, the energy per unit weight of butanol is higher than the method of the present disclosure.
　４．効果
　本開示のブタノールの濃縮脱水方法によれば、実質的に抽出溶媒と水分とを含まないブタノールを得るために要するエネルギーを低減することができる。 4). Effect According to the method for concentrating and dehydrating butanol according to the present disclosure, it is possible to reduce energy required to obtain butanol substantially free from an extraction solvent and moisture.
　また、本開示のブタノールの濃縮脱水方法は、必ずしも透過膜を使用しなくてもよいので、透過膜に関する問題が生じにくい。また、本開示のブタノールの濃縮脱水方法は、必ずしも２オクタノールを使用しなくてもよいので、２オクタノールを無害な溶媒で抽出分離する工程が必須ではない。 Also, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of a permeable membrane, so that problems relating to the permeable membrane are unlikely to occur. In addition, the butanol concentration and dehydration method of the present disclosure does not necessarily require the use of 2 octanol, and therefore a step of extracting and separating 2 octanol with a harmless solvent is not essential.
　以上、本開示の実施形態について説明したが、本開示は上記実施形態に限定されることなく、種々の形態を採り得る。
　例えば、ブタノール水溶液は、発酵ブタノール（バイオブタノール）水溶液であってもよい。また、ブタノール水溶液は、アセトン、エタノール、又はその両方を含んでいてもよい。また、本開示により得られる精製物は、ブタノールと他の成分（例えば、アセトン、エタノール、又はその両方等）とを含む混合液であってもよい。 As mentioned above, although embodiment of this indication was described, this indication can take various forms, without being limited to the above-mentioned embodiment.
For example, the butanol aqueous solution may be a fermented butanol (biobutanol) aqueous solution. The butanol aqueous solution may contain acetone, ethanol, or both. The purified product obtained by the present disclosure may be a mixed solution containing butanol and other components (for example, acetone, ethanol, or both).

Claims (2)

  1. 　ブタノール水溶液と、ブタン、イソペンタン、及びノルマルペンタンから成る群から選択される１種以上である抽出溶媒とを、抽出温度Ｔ及び抽出圧力Ｐの条件下で接触させ、前記抽出溶媒、及び抽出されたブタノールを含む抽出物を取り出す抽出工程と、
    　前記抽出物を、蒸留により、ブタノール、水、及び前記抽出溶媒を含む気相成分と、ブタノールを含む液相成分とに分離するとともに、前記気相成分に含まれるブタノールを液状の前記抽出溶媒により抽出し、抽出されたブタノールを前記液相成分に加え、前記液相成分を取り出す分離工程と、
    　を備え、
    　前記抽出温度Ｔは、１００～２５０℃の範囲内であり、且つ前記抽出溶媒の臨界温度をＴｃとしたとき、前記抽出温度Ｔは０．９５Ｔｃ以下であり、
    　前記抽出圧力Ｐは、前記抽出温度Ｔにおける前記抽出溶媒の蒸気圧以上であるブタノールの濃縮脱水方法。     An aqueous solution of butanol and one or more extraction solvents selected from the group consisting of butane, isopentane, and normal pentane were brought into contact with each other under the conditions of extraction temperature T and extraction pressure P, and the extraction solvent and extracted An extraction step of extracting an extract containing butanol;
    The extract is separated by distillation into a gas phase component containing butanol, water, and the extraction solvent and a liquid phase component containing butanol, and the butanol contained in the gas phase component is separated by the liquid extraction solvent. A separation step of extracting and adding the extracted butanol to the liquid phase component and taking out the liquid phase component;
    With
    The extraction temperature T is in the range of 100 to 250 ° C., and when the critical temperature of the extraction solvent is Tc, the extraction temperature T is 0.95 Tc or less,
    The butanol concentration dehydration method, wherein the extraction pressure P is equal to or higher than the vapor pressure of the extraction solvent at the extraction temperature T.
  2. 　前記抽出工程では、抽出塔の上部からブタノール水溶液を供給し、前記抽出塔の下部から前記抽出溶媒を供給し、前記ブタノール水溶液及び前記抽出溶媒を向流接触させる請求項１に記載のブタノールの濃縮脱水方法。 2. The concentration of butanol according to claim 1, wherein in the extraction step, a butanol aqueous solution is supplied from an upper part of the extraction tower, the extraction solvent is supplied from a lower part of the extraction tower, and the butanol aqueous solution and the extraction solvent are brought into countercurrent contact. Dehydration method.
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