KR20190019060A - A process for producing isopropyl alcohol and a process for producing isopropyl alcohol - Google Patents

Abstract

A process for producing isopropyl alcohol wherein water is directly hydrated to propylene to produce isopropyl alcohol, wherein the ratio of propylene and water in the reactor at the time of reacting propylene with water in the reactor is adjusted to be 100 parts by mass To 1300 to 2100 parts by mass, and the residence time of water in the reactor is from 20 minutes to 50 minutes or less.

Description

A process for producing isopropyl alcohol and a process for producing isopropyl alcohol

The present invention relates to a novel process for producing isopropyl alcohol and to isopropyl alcohol with reduced impurities.

Isopropyl alcohol (also referred to as 2-propanol) has a property of dissolving both water and an organic solvent, and is widely used as a solvent for paints and inks. Particularly, isopropyl alcohol in which impurities are reduced is also used for cleaning and drying electronic devices, and an increase in the amount of use is expected in the future.

Examples of the method for producing isopropyl alcohol include an acetone reducing method for reducing acetone; An indirect hydration method in which propylene is esterified using concentrated sulfuric acid and then hydrolyzed; A direct hydration method in which propylene is directly hydrated in the presence of a catalyst; Are known. In particular, the direct hydration method has an advantage that inorganic acids such as sulfuric acid are not used as compared with the indirect hydration method. Thus, in recent years, the production of isopropyl alcohol by direct hydration has become mainstream.

For example, Non-Patent Document 1 describes a fixed bed catalyst method and a solution catalyst method in an industrialized process of direct hydration. More concretely, three types of production methods are described by the vapor phase method of the fixed bed catalytic method, the Deutsche Texaco method by the gas-phase mixing method of the fixed bed catalysis method and the liquid phase method of the solution catalyst method by the Veba Chemie method, the Tokuyama soda method .

The production process of the Veba Chemie method is a process in which isopropyl alcohol is synthesized in the order of a reactor, a scrubber (unreacted propylene recovery), a low-boiling tower, an azeotropic tower, and a dehydration tower Separation, and purification. In the Veba Chemie method, since the feed ratio of water and propylene is reacted in an equal amount, the amount of unreacted water is small, and water contained in the reaction mixture is reduced. Therefore, in the Veba Chemie method, unreacted material is not recovered but treated as wastewater.

Further, the production process of the Deutsche Texaco method is to synthesize, separate and purify isopropyl alcohol in the order of the reactor, the separator (unreacted propylene recovery), the low-temperature tower, the azeotropic tower and the dehydration tower. In the Deutsche Texaco method, a strong acidic styrene-type cation exchange resin is used as a catalyst in the reactor, so that the sulfuric acid derived from the cation exchange resin is contained in the reaction mixture. Thereafter, in the azeotropic column, water containing sulfuric acid and isopropyl alcohol are separated and water containing sulfuric acid is recovered. However, when water containing sulfuric acid is directly reused as a raw material, sulfuric acid is concentrated in the production process It is not preferable because it is discarded. Therefore, in the Deutsche Texaco method, after the water containing sulfuric acid is recovered, the sulfuric acid contained in the recovered water is removed by neutralization and desalting.

The production process of the Tokuyama soda method is a process in which isopropyl alcohol is synthesized in the order of a reactor, a separator (unreacted propylene recovery), an azeotropic tower, a low-tower, a dehydration tower, a recovery tower, will be. In Tokuyama Soda Law, water is recovered from the bottom of the tower of the azeotropic tower, and the recovered water is reused as raw material.

However, since isopropyl alcohol forms an azeotropic mixture with water in the presence of water, it is difficult to remove water contained in isopropyl alcohol only by the production process described in Non-Patent Document 1, and to remove impurities dissolved in water and water I do not. Therefore, improvement of the distillation process has heretofore been attempted (see, for example, Patent Document 1).

Further, since it is difficult to remove metal cations and the like contained in isopropyl alcohol only by the distillation step, a filtration step is added to the post-step of the distillation step to remove impurities contained in isopropyl alcohol by a filter (See, for example, Patent Document 2).

A method of purifying isopropyl alcohol by a method other than the improvement of the distillation step and a method of removing moisture contained in isopropyl alcohol by using the molecular sieve effect of zeolite-based particles or silica-based particles is also proposed (See, for example, Patent Document 3).

Also in the acetone reduction method, there is proposed a method for improving the selectivity and the conversion rate by improving the reaction conditions of the hydrogenation catalyst, thereby suppressing the by-products other than the reaction target and reducing the impurities contained in the isopropyl alcohol (See, for example, Patent Document 4).

In particular, Patent Document 4 discloses that 4-methyl-2-pentanol and 2-methylpentane-2, 4-diol as impurities are reduced. In Example 1, the impurity concentration in the isopropyl alcohol Standard is 1 ppm of 4-methyl-2-pentanol and 21 ppm of 2-methylpentane-2, 4-diol.

However, as a method for producing isopropyl alcohol described in Patent Documents 1 to 4, isopropyl alcohol in which impurities are further reduced can not be produced, and further reduction of impurities has been required. For example, in an electronic device manufacturing process, if isopropyl alcohol containing impurities of several ppm is used in the cleaning process, residues derived from isopropyl alcohol remain on the surface of the electronic device after cleaning and drying, Isopropyl alcohol with very little impurities is required.

Patent Document 1: Japanese Patent Specification No. 2003-535836 Patent Document 2: Japanese Patent Publication No. 07-116079 Patent Document 3: Japanese Patent Specification No. 2015-524818 Patent Document 4: International Publication No. 2009/104597

Non-Patent Document 1: Organic Synthesis Chemical Society, Vol. 35 (9), 761-766 (1977)

As described above, the impurity concentration of the isopropyl alcohol purified by the conventional method is insufficient for use in the recent electronic device manufacturing process, and a method for producing isopropyl alcohol capable of further reducing the impurity concentration and a method for reducing the impurity concentration Isopropyl alcohol was required.

In addition, when isopropyl alcohol is synthesized by a direct hydration method, an indirect hydration method, or an acetone reduction method, which is conventionally known as a method for producing isopropyl alcohol, and then isopropyl alcohol is purified by a distillation step or a filtration step after the synthesis reaction, A few ppm of impurities derived from the by-products during the reaction are contained in the purified isopropyl alcohol. Therefore, in order to remove impurities of the order of several ppm, impurities can be reduced by a simple method without increasing the cost of equipment and energy, and at the same time, it has been a great challenge to improve the yield of isopropyl alcohol.

The present inventors have conducted extensive studies to solve the above problems. As a result, among the impurities contained in isopropyl alcohol used in the production process of the electronic device, impurities which should be particularly noticed are high boiling point compounds having a boiling point higher than that of isopropyl alcohol. Among these high boiling point compounds, And the ratio of the high boiling point compound via the propylene oligomer generated by the reaction was high. Among these high-boiling point compounds, preferred are 1,2-propanediol, 4-methyl-2-pentanol, 2-methyl-3-pentanone, 2-butanol, 2-methyl-2-pentanol, 3-methyl-3-pentanol, 2-methyl- Pentanol, 2-ethyl-1-pentanol, 2-methyl-2-pentanol, High boiling point compounds such as 1-pentanol, 3-methyl-1-pentanol, 4-methyl-1-pentanol, 2-methyl-2,4-pentanediol and 2,3- And the ratio of the high-boiling point compounds having 5 to 12 carbon atoms is particularly high.

Therefore, in order to suppress the production of the propylene oligomer as a raw material of the high boiling point compound in the reaction step of reacting propylene and water in the direct hydration method of isopropyl alcohol, water is excessively supplied to propylene, and propylene and water It has been found that by appropriately controlling the reaction time, generation of a high boiling point compound involving the propylene oligomer in the reaction step can be suppressed.

In addition, it is also possible to carry out a recovery step of recovering propylene from the reaction mixture obtained in this reaction step, a first distillation step of removing a low boiling point compound having a boiling point lower than isopropyl alcohol from the reaction mixture in which propylene is recovered in the recovery step, The second distillation step of removing water from the reaction mixture from which the low-boiling point compound has been removed is carried out, so that impurities can be reduced by a simple method without removing various equipment costs or energy costs to remove impurities of several ppm And thus the present invention has been accomplished.

More specifically, the ratio of propylene and water in the reactor is set to 1300 to 2100 parts by mass with respect to 100 parts by mass of propylene, and the residence time of water in the reactor is changed from 20 minutes to 50 minutes or less Thus, it has been found that the production of propylene oligomer is suppressed without lowering the yield of isopropyl alcohol and the high boiling point compound having a boiling point higher than that of isopropyl alcohol can be reduced.

That is, the present invention relates to a process for producing isopropyl alcohol which directly hydrolyzes water to propylene to produce isopropyl alcohol, the process comprising: a feed step of feeding propylene and water having a pH of 2.5 to 4.5 into a reactor; A reaction step of reacting propylene with water in the reactor; A recovery step of recovering propylene from the reaction mixture obtained in the reaction step; A first distillation step of removing a low boiling point compound having a boiling point lower than isopropyl alcohol from the reaction mixture in which the propylene is recovered in the recovery step; And a second distillation step of removing water from the reaction mixture from which the low boiling point compound has been removed in the first distillation step to obtain isopropyl alcohol, wherein the ratio of propylene and water in the reactor is 100 parts by mass Wherein the water content in the reactor is 1300 to 2100 parts by mass and the residence time of water in the reactor is more than 20 minutes but not more than 50 minutes.

The present invention also provides isopropyl alcohol, wherein the concentration of 4-methyl-2-pentanol, 2-methyl-3-pentanone, and 4-methyl-2-pentanone as impurities are all 20 ppb or less by mass do.

According to the production process of the present invention, production of propylene oligomer can be suppressed without lowering the yield of isopropyl alcohol, and the selectivity from propylene to isopropyl alcohol can be increased.

Further, according to the production method of the present invention, it is possible to produce isopropyl (meth) acrylate having a concentration of 4-methyl-2-pentanol, 2-methyl-3-pentanone, Alcohol can be produced.

According to the present invention, since the generation of by-products is suppressed in the reaction of directly hydrating propylene with water, the load on the purification step after the synthesis reaction is reduced, and the distillation step for removing impurities and the filtration step can be simplified have.

As described above, according to the present invention, it is possible to industrially produce isopropyl alcohol with reduced impurities.

1 is a schematic diagram showing an example of a process for producing isopropyl alcohol of the present disclosure.

≪ Production method of isopropyl alcohol >

As shown in Fig. 1, the process for producing isopropyl alcohol of the present disclosure (hereinafter also referred to as " production process of the present disclosure ") includes a raw material supply step, a reaction step, a recovery step for recovering propylene, And a second distillation step for recovering water. Hereinafter, each step will be described in detail.

[Material Feeding Process]

The raw materials used in the production method of the present disclosure are propylene and water. As shown in Fig. 1, propylene as a raw material is accommodated in a recovery tank, mixed with propylene recovered in a recovery process and a recovery tank, and fed to the reactor. Similarly, the water to be the raw material is contained in the recovery tank, and the water recovered in the second distillation step is mixed in the recovery tank and supplied to the reactor.

In the production process of the present disclosure, propylene having a purity of 95% by mass or more, which is generally available as an industrial product, can be used as the raw material, and propylene having a purity of 98% by mass or more is preferably used. When propylene contains unsaturated hydrocarbon compounds such as ethylene, butene, pentene, and hexene, they are subjected to a hydration reaction in the reaction step to become impurities, so that the purity of propylene as a raw material is preferably high. However, according to the production method of the present disclosure, it is not necessary to use propylene of high purity exceeding 99 mass%, since the conversion of propylene and the selectivity to isopropyl alcohol can be increased. The purity of propylene as a raw material may be 95 to 99 mass% or 98 to 99 mass%.

In addition, the catalyst required in the reaction step can be added in advance to the raw water. Examples of the catalyst include various polyanion catalysts such as molybdenum-based inorganic ion exchangers and tungsten-based inorganic ion exchangers. The catalyst may be used singly or in combination of two or more. Among these catalysts, at least one member selected from the group consisting of tungstic acid (lignan stenoic acid), silicotungstic acid (citronutstonic acid), and silicomolybdic acid (silicomolybdic acid) is preferable from the viewpoint of the reaction activity.

It is preferable that the pH of the water used as the raw material is measured by a pH meter and the pH is adjusted to 2.5 to 4.5 at 25 ° C. It is possible to obtain a reaction condition optimal for obtaining a high selectivity to isopropyl alcohol while maintaining the conversion rate of propylene at a high level by adding a catalyst so that the pH of the raw water becomes in the range of 2.5 to 4.5. It is possible to inhibit the generation.

When the measured pH is less than 2.5, the pH can be adjusted by adding an alkali such as sodium hydroxide. On the other hand, when the pH exceeds 4.5, the pH can be easily adjusted by adding a catalyst. With such a pH range, it is possible to suppress the piping by the acid and the corrosion of the reactor, and therefore the concentration of the metal ion contained in the isopropyl alcohol can be suppressed.

[Reaction Process]

The direct hydration reaction of propylene in the reaction step is expressed by the following equation. The following reaction is carried out in a reactor to obtain a reaction mixture.

C ₃ H ₆ + H ₂ O → CH ₃ CH (OH) CH ₃

In Non-Patent Document 1, the Tokuyama soda method is exemplified by the vapor phase method of the fixed bed catalytic method, the Deutsche Texaco method by the gas phase mixing method of the fixed bed catalytic method, and the liquid phase method of the solution catalytic method by the Veba Chemie method, This is a method for improving the catalytic method. Therefore, as the reaction conditions, it is preferable to set the reaction pressure to 150 to 250 atm, preferably 180 to 250 atm, and the reaction temperature to 200 to 300 ° C, preferably 250 to 280 ° C. By satisfying the reaction conditions within this range, there is a tendency to be able to combine the yields of industrially produced products and the durability of catalyst while suppressing the production of by-products.

In the direct hydration reaction of propylene in the reaction step, 1 mol of isopropyl alcohol is produced from 1 mol of propylene and 1 mol of water as shown in the above chemical reaction formula. Therefore, usually, propylene and water may be equivalent, but in the manufacturing method of the present disclosure, water is excessively added to propylene. Concretely, water is changed to 1300 to 2100 parts by mass with respect to 100 parts by mass of propylene. By setting the ratio of propylene and water in the reactor within the above range, the production of propylene oligomer can be suppressed and the yield of isopropyl alcohol can be increased. In addition, the production efficiency of isopropyl alcohol can be increased. The amount of water relative to 100 parts by mass of propylene is preferably 1500 to 2000 parts by mass.

Here, when the ratio of water to 100 parts by mass of propylene is less than 1300 parts by mass, it is difficult to inhibit the production of propylene oligomer, and the impurity concentration of isopropyl alcohol tends to increase. On the other hand, when the ratio of water to 100 parts by mass of propylene exceeds 2100 parts by mass, a large amount of water which does not substantially contribute to the improvement of the selectivity is present in the recovery step after the reaction step, The thermal energy required becomes large, which is disadvantageous from the viewpoint of cost. The concentration of isopropyl alcohol in the reaction mixture after recovery of propylene is preferably 5.5% by mass or more, and more preferably 6.0% by mass or more. When the concentration is in this range, both the purity and the yield of isopropyl alcohol tend to be improved.

In the manufacturing method of the present disclosure, in order to improve both the concentration and the purity of isopropyl alcohol in the reaction mixture obtained by the reaction step, the residence time of water in the reactor is set to be not less than 20 minutes and not more than 50 minutes. The residence time of the water is preferably 25 to 40 minutes, more preferably 30 to 40 minutes.

Here, when the residence time of water in the reactor is less than 20 minutes, the yield of isopropyl alcohol tends to be lowered, resulting in poor economical efficiency. On the other hand, when the residence time of water in the reactor exceeds 50 minutes, the selectivity of isopropyl alcohol decreases and the purity of isopropyl alcohol tends to be lowered by the increase of by-products. That is, when the residence time of the water in the reactor becomes long, the unreacted propylene is oligomerized and further the hydroxyl group or the ketone group is added, or the unreacted propylene reacts with the unsaturated hydrocarbon compound as the impurity. Further, the synthesized isopropyl alcohol reacts to form a dimer, or propylene or propylene oligomer as a raw material is added to isopropyl alcohol. It is presumed that the side reaction is progressed by this sequential side reaction, thereby increasing the by-product.

The residence time of water in the present disclosure is a time defined by the following formula, and can be suitably changed by changing the supply amount of the water to be the raw material and the volume of the reactor.

(Min) = volume of reactor (m ³ ) ÷ amount of water supplied (m ³ / min)

Since the reaction in the reactor in this disclosure is carried out under high temperature and high pressure, the density of water is unclear. Therefore, the supply amount of water is calculated on the basis of the flow rate of water (110 DEG C in the following embodiment) supplied into the reactor.

[Recovery process]

The isopropyl alcohol produced in the above reaction step is extracted from the reactor in a state of being dissolved in an aqueous phase. Then, the pressure and the temperature are lowered in the recovery step, propylene dissolved in the water phase is extracted by gas, and propylene is recovered. For this recovery process, the technique established by the separator of unreacted propylene can be applied. The recovered propylene is recycled to the propylene recovery tank in the raw material supplying step and reused as a raw material.

Further, in the production method of the present disclosure, since large heat energy is required in the reaction step, the distillation step, etc., the recovered propylene can be used as a heat energy source.

[First distillation step]

In the first distillation step, a distillation operation is performed for the purpose of removing a low boiling point compound having a boiling point lower than that of isopropyl alcohol from the reaction mixture in which the propylene is recovered in the recovery step. In the production process of the present disclosure, since isopropyl alcohol is synthesized under the condition that water is excessive, low boiling point compounds (for example, olefins such as ethylene and propylene, acetone, Diisopropyl ether, etc.) are included in a large amount in comparison with the conventional production methods.

In general, it is advantageous to remove the low boiling point compound after separating water and isopropyl alcohol from the viewpoint of the energy required for the distillation column. However, in the production method of the present disclosure, The compound is removed.

[Second distillation step]

In the second distillation step, a distillation operation is performed for the purpose of removing water from the reaction mixture from which the low boiling point compound has been removed in the first distillation step to obtain isopropyl alcohol. The azeotropic temperature of water and isopropyl alcohol is 80 캜. In the second distillation step, isopropyl alcohol containing about 13% by mass of water is extracted from the column top, and further dehydration is carried out if necessary. On the other hand, in the column bottom, excess water is extracted and recovered.

The water recovered in the second distillation step is preferably used as a raw material for isopropyl alcohol since the low boiling point compound having a boiling point lower than that of isopropyl alcohol is removed in the first distillation step, which is the major distillation step. The recovered water is recycled to the water recovery tank in the raw material supplying step and reacted with propylene under the synthetic condition in which water becomes excessive, so that high purity isopropyl alcohol with reduced by-products can be produced.

[Other Process]

The isopropyl alcohol in which the impurities obtained in the second distillation step is reduced can be further made into isopropyl alcohol with reduced impurities by further performing a dehydration process and a purification process. In addition to dehydration and purification, metal or inorganic particles may be removed by a filtering process, or metal ions may be removed by an ion exchange resin column. By removing impurities other than the organic compounds after distillation, isopropyl alcohol which can be preferably used for cleaning of electronic devices and the like can be produced.

As a result of suppressing the generation of by-products in the reaction step by the above-described production method, it is possible to reduce the concentration of the impurities in the purification step after the reaction step, that is, in the distillation step or the filtration step, Lt; / RTI >

<Isopropyl alcohol with reduced impurities>

In the isopropyl alcohol of the present disclosure, the concentrations of 4-methyl-2-pentanol, 2-methyl-3-pentanone and 4-methyl-2-pentanone as impurities are all 20 ppb or less on a mass basis.

The isopropyl alcohol of the present disclosure can be used as an impurity such as 1,2-propanediol, 3-methyl-2-pentanone, 2-hexanone, 3,3- Propanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 3-methyl- Pentanol, 2-methyl-1-pentanol, 2-methyl-1-pentanol, 2-methyl- -Methyl-2,4-pentanediol, and the concentration of 2,3-dimethyl-2,3-butanediol are all preferably 20 ppb or less on a mass basis.

It is preferable that the isopropyl alcohol of the present disclosure has a boiling point higher than that of isopropyl alcohol and that the concentration of the high boiling point compound as an impurity having 5 to 12 carbon atoms is 20 ppb or less on a mass basis.

It is preferable that the isopropyl alcohol of the present disclosure has a boiling point higher than that of isopropyl alcohol and that the concentration of the high boiling point compound as an impurity having 5 to 30 carbon atoms is 500 ppb or less on a mass basis.

The isopropyl alcohol of the present disclosure has a high boiling point impurity concentration that is lower than that of isopropyl alcohol. Therefore, the isopropyl alcohol can be used in various cleaning applications, and particularly, it can be preferably used as a cleaning liquid for electronic devices. Impurities having a boiling point higher than that of isopropyl alcohol are difficult to remove in the drying step after the cleaning step and are likely to remain on the surface of the electronic device. By using isopropyl alcohol of the present disclosure, residues remaining on the surface of the electronic device after cleaning and drying Can be reduced.

The isopropyl alcohol of the present disclosure can be produced, for example, by the production method of the present disclosure described above.

It is presumed that the high boiling point compound as the impurity is derived from the by-product resulting from the side reaction of the direct hydration reaction. That is, since isopropyl alcohol is synthesized using propylene having a carbon number of 3 as a raw material, side reactions such as a side reaction for producing a dimer of propylene and a side reaction for producing a dimer of isopropyl alcohol can be considered. Therefore, in the case of isopropyl alcohol, in particular, a hydrocarbon compound having 6, 9, or 12 carbon atoms is often included as an impurity. In addition, since water exists in the reaction field of the side reaction, a hydroxyl group or a ketone group may be introduced into the by-product. Therefore, an alcohol in which a hydroxyl group is introduced into a hydrocarbon compound having 6, 9, or 12 carbon atoms, or a ketone into which a ketone group is introduced may be contained as an impurity.

In the conventional production method, since the reaction conditions are adjusted so that the concentration of isopropyl alcohol is maximized in the reaction step by seeking only the yield of isopropyl alcohol, the obtained isopropyl alcohol contains a relatively large amount of impurities. Although it was possible to reduce the impurity concentration to about 1 ppm on the mass basis by the distillation step after the reaction step, it was difficult to further reduce the impurity concentration by the distillation step alone.

On the other hand, according to the manufacturing method of the present disclosure, the ratio of propylene and water in the reactor is set to 1300 to 2100 parts by mass with respect to 100 parts by mass of propylene, and the residence time of water in the reactor is changed from 20 minutes to 50 minutes Or less, the selectivity to isopropyl alcohol can be increased while maintaining the yield of isopropyl alcohol. As a result, high purity of isopropyl alcohol can be easily achieved without overloading the process for purifying isopropyl alcohol.

Further, by adjusting the conditions of the production method of the present disclosure, the total amount of impurities contained in isopropyl alcohol can be made smaller. For example, the sum of the concentrations of high boiling point compounds as impurities having a higher boiling point than isopropyl alcohol and having 5 to 12 carbon atoms is preferably 1 ppm or less, more preferably 100 ppb or less, 20 ppb or less, particularly preferably 10 ppb or less.

Further, according to the production method of the present disclosure, the concentration of a salt having an organic acid skeleton having 10 or less carbon atoms as an impurity and a derivative thereof can be reduced.

Further, according to the production method of the present disclosure, since the low boiling point compound is discharged out of the system in the first distillation step and the second distillation step after the reaction step, the concentration of the low boiling point compound as well as the high boiling point compound can be reduced. Examples of low boiling point compounds include straight chain hydrocarbon compounds having 4 or 5 carbon atoms, which are included as impurities in propylene as a raw material, for example, straight chain alkanes such as butane, pentane, and hexane. Other examples of the low boiling point compounds include propylene oligomers derived from propylene as raw material and diisopropyl ether.

Example

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. In the following description, "%", "ppm", and "ppb" denoting the concentration are all on a mass basis.

<Concentration method>

Since isopropyl alcohol of the present disclosure has reduced impurities, it is necessary to concentrate isopropyl alcohol to be measured as needed to improve the analysis precision. Although the concentration method is shown below, the following operations may be repeated as necessary to change the magnification of concentration. As the concentration condition of the high boiling point compound, distillation is carried out for 24 hours, for example, at a top temperature of the distillation tower at about 82 ° C in a precision distillation apparatus. The number of theoretical stages in the precision distillation apparatus is 2 to 30 stages, and if it is a singular value in this range, distillation and concentration can be performed.

By performing distillation at about 82 占 폚 for 24 hours, it is possible to concentrate to 76 times. Further, in order to prevent the oxidation of the object of analysis, it is preferable to circulate nitrogen in advance in the precision distillation apparatus to make it an inert atmosphere. During the distillation, it is preferable that nitrogen is also passed through the liquid aggregate portion storing the effluent (distillate) after distillation, and distilled under an inert atmosphere.

It is also possible to carry out distillation and concentration by raising the reflux ratio of the precision distillation apparatus to a large extent and obtaining an effluent from the column top. If necessary, isopropyl alcohol may be added to the vial and nitrogen may be passed through the upper part of the liquid surface to further concentrate the high boiling point compound 10 times. For example, when the precision distillation apparatus and the concentration in the vial are combined, 76 × 10 = 760, which corresponds to a concentration of 760 times.

<Method of measuring impurities>

[Method for measuring high boiling point compounds (qualitative analysis)]

In the present disclosure, the high boiling point compound contained in isopropyl alcohol was measured under the following measurement conditions using a gas chromatography-mass spectrometer (hereinafter referred to as "GC-MS").

-Measuring conditions-

Devices: Agilent Technologies, Inc., 7890A / 5975C

Analytical column: SUPELCO WAX-10 (60 m x 0.25 mm, 0.25 m)

Column temperature: 35 占 폚 (held for 2 minutes)? Elevated temperature at 5 占 폚 / min? Elevated temperature at 100 占 폚? 10 占 폚 / min? 240 占 폚

Carrier gas: helium

Carrier gas flow rate: 2 mL / min

Inlet temperature: 240 ° C

Sample injection method: pulsed splitless method

Pulse pressure at injection: 90 psi (2 min)

Split vent flow rate: 50 mL / min (2 min)

Gas Saver use: 20 mL / min (5 min)

Transfer line temperature: 240 ° C

Ion source, quadrupole temperature: 230 ° C, 150 ° C

Scanning ion: m / Z = 25-250

In the case where isopropyl alcohol was not concentrated and no peak was detected in a region having a longer holding time than isopropyl alcohol in the chart obtained according to the above conditions, the concentration of the high boiling point organic substance having 5 to 30 carbon atoms was 500 ppb Or less.

[Method for measuring high boiling point compounds (quantitative analysis)]

When a peak was confirmed on the chart obtained by the method of qualitative analysis, library search was performed from the mass spectrum of the peak to specify the structure. The concentration of the high boiling point organics detected by qualitative analysis was then quantified by selective ion detection (SIM), by preparing the specified standard of high boiling point organic matter and comparing it to the peak area of a pre-determined reference material.

-SIM Monitor Ion-

Group 1 Start Time: 12.7 min, m / Z: 31, 43, 75 (dwell 60)

Group 2 start time: 13.5 minutes, m / Z: 45, 56, 75, 59 (dwell 45)

Group 3 Start time: 16.0 min, m / z: 42, 43, 56 (dwell 60)

Group 4 Start Time: 22.0 min, m / z: 45, 56, 59, 72 (dwell 45)

[Measurement method of low boiling point compound (qualitative analysis)]

In the present disclosure, low boiling point compounds contained in isopropyl alcohol were measured under the measurement conditions shown below using GC-MS.

-Measuring conditions-

Devices: Agilent Technologies, Inc., 7890A / 5975C

Analytical column: SUPELCO WAX-10 (60 m x 0.25 mm, 0.25 m)

Column temperature: 35 占 폚 (held for 2 minutes)? Elevated temperature at 5 占 폚 / min? Elevated temperature at 100 占 폚? 10 占 폚 / min? 240 占 폚

Carrier gas: helium

Carrier gas flow rate: 2 mL / min

Inlet temperature: 240 ° C

Sample injection method: Split method

Split ratio: 1 to 10

Transfer line temperature: 240 ° C

Ion source, quadrupole temperature: 230 ° C, 150 ° C

Scanning ion: m / Z = 25-250

If the peak is not detected in a region having a shorter holding time than isopropyl alcohol in the chart obtained according to the above conditions when isopropyl alcohol is not concentrated, it can be estimated that the concentration of the low boiling point organic substance is 5000 ppm or less which is the lower limit of detection.

[Method for measuring low boiling point compounds (quantitative analysis)]

Similarly to the quantitative analysis of the high-boiling point compound, when a peak was confirmed in the chart obtained by the qualitative analysis method, library search was performed from the peak mass spectrum to specify the structure. The concentration of the low boiling point organism detected by qualitative analysis was then quantified by selective ion detection (SIM), by preparing the specified standard of low boiling point organic matter and comparing it with the peak area of a pre-determined reference material.

-SIM Monitor Ion-

m / Z: 29 (acetaldehyde analysis)

m / Z: 58 (acetone, analysis of propionaldehyde)

&Lt; Example 1 >

[Production of isopropyl alcohol]

As the raw material propylene, propylene containing 39972 ppm of propane, 20 ppm of ethane, 8 ppm of butene, 0.1 ppm or less of pentene, and 0.1 ppm or less of hexene was prepared as an impurity as shown in Table 1. As the raw material water, tungstic acid, which is a catalyst, was added to adjust the pH to 3.0.

At the same time, which also put the feed rate of, in reactors having small contents of 10 L, heated water to 18.4 kg / h to 110 ℃ (because the density ^{920 kg / m 3, 20 L} / h) , depending on the manufacturing process shown in Figure 1, Propylene was fed at a feed rate of 1.2 kg / h (raw material feeding step).

The residence time of water in the reactor at this time is 30 minutes, and 1500 parts by mass of water is supplied to 100 parts by mass of propylene. Propylene and water were reacted at a reaction temperature of 280 ° C in the reactor and a reaction pressure of 250 atm to obtain isopropyl alcohol (reaction step).

Subsequently, the reaction mixture containing isopropyl alcohol produced in the reaction step was cooled to 140 DEG C and the pressure was reduced to 18 atm to recover propylene dissolved in water contained in the reaction mixture as a gas (recovery step) . The recovered propylene was put into a recovery tank of propylene for reuse as a raw material.

In the reaction mixture in which propylene was recovered, the conversion of propylene was 84.0%, the selectivity of propylene to isopropyl alcohol was 99.2%, and the concentration of isopropyl alcohol was 7.8%.

Subsequently, a low boiling point compound having a boiling point lower than that of isopropyl alcohol was removed from the reaction mixture after the recovery of propylene by using a distillation column (first distillation step).

Subsequently, the reaction mixture was extracted from the column bottom of the distillation column and separated into water and isopropyl alcohol using a distillation column (second distillation step).

The recovered water extracted from the bottom of the column was put into a water recovery tank for reuse as a raw material under conditions of a temperature of 110 ° C and a pressure of 1.5 atm. Adjustment was also performed by adding tungstic acid so that the pH of the recovered water was maintained at 3.0.

On the other hand, isopropyl alcohol extracted from the column top contains about 13% of water. Therefore, a distillation process for dehydration and a distillation process for purifying isopropyl alcohol were performed to obtain isopropyl alcohol.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.3 ppm of 1-propanol and 4 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentrations of 4-methyl-2-pentanol, 2-methyl-3-pentanone, and 4-methyl-2-pentanone as impurities were all lower than the detection limit of 20 ppb. Likewise, it is possible to use, as impurities, 1, 2-propanediol, 3-methyl-2-pentanone, 2-hexanone, 3,3- Pentanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, - pentanediol, and 2,3-dimethyl-2,3-butanediol were all lower than the detection limit of 20 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

The tertiary butanol contained in the high boiling point compound was derived from butene contained in the raw material propylene but could not be separated because the boiling point was 82.4 캜 which is the same as that of isopropyl alcohol.

&Lt; Example 2 >

[Production of isopropyl alcohol]

Except that the supply amount of water was 13.8 kg / h (the density was 920 kg / m ^{3 and} therefore 15 L / h), the amount of propylene supplied was 0.9 kg / h, and the residence time of water in the reactor was 40 minutes. In the same manner as in Example 1, isopropyl alcohol was produced.

Then, in the reaction mixture in which propylene was recovered, the conversion of propylene was 86.4%, the selectivity of propylene to isopropyl alcohol was 98.9%, and the concentration of isopropyl alcohol was 8.0%.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.4 ppm of 1-propanol and 4 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentrations of 4-methyl-2-pentanol, 2-methyl-3-pentanone, and 4-methyl-2-pentanone as impurities were all lower than the detection limit of 20 ppb. Likewise, it is possible to use, as impurities, 1, 2-propanediol, 3-methyl-2-pentanone, 2-hexanone, 3,3- Pentanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, - pentanediol, and 2,3-dimethyl-2,3-butanediol were all lower than the detection limit of 20 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

&Lt; Example 3 >

[Production of isopropyl alcohol]

Propylene as the raw material, propylene as the impurity, propane at the rate of 19956 ppm, ethane at 40 ppm, butene at the rate of 4 ppm, pentene at the rate of 0.1 ppm or less and hexene at the rate of 0.1 ppm or less were contained as the impurities, , And isopropyl alcohol.

In the reaction mixture in which propylene was recovered, the conversion of propylene was 84.3%, the selectivity of propylene to isopropyl alcohol was 99.1%, and the concentration of isopropyl alcohol was 8.0%.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.3 ppm of 1-propanol and 2 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentrations of 4-methyl-2-pentanol, 2-methyl-3-pentanone, and 4-methyl-2-pentanone as impurities were all lower than the detection limit of 20 ppb. Likewise, it is possible to use, as impurities, 1, 2-propanediol, 3-methyl-2-pentanone, 2-hexanone, 3,3- Pentanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, - pentanediol, and 2,3-dimethyl-2,3-butanediol were all lower than the detection limit of 20 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

<Example 4>

[Production of isopropyl alcohol]

Except that the supply amount of water was 18.4 kg / h (the density was 920 kg / m ^{3 and} therefore, 20 L / h), the amount of propylene supplied was 0.9 kg / h, and the amount of water supplied to 100 parts by mass of propylene was 2000 parts , And isopropyl alcohol was prepared in the same manner as in Example 1.

In the reaction mixture in which propylene was recovered, the conversion of propylene was 86.2%, the selectivity of propylene to isopropyl alcohol was 99.2%, and the concentration of isopropyl alcohol was 6.0%.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.2 ppm of 1-propanol and 4 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentrations of 4-methyl-2-pentanol, 2-methyl-3-pentanone, and 4-methyl-2-pentanone as impurities were all lower than the detection limit of 20 ppb. Likewise, it is possible to use, as impurities, 1, 2-propanediol, 3-methyl-2-pentanone, 2-hexanone, 3,3- Pentanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, 1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, - pentanediol, and 2,3-dimethyl-2,3-butanediol were all lower than the detection limit of 20 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

&Lt; Comparative Example 1 &

[Production of isopropyl alcohol]

Except that the supply amount of water was 18.4 kg / h (the density was 920 kg / m ^{3 and} therefore, 20 L / h), the amount of propylene supplied was 1.5 kg / h, and the amount of water supplied to 100 parts by weight of propylene was 1200 parts , And isopropyl alcohol was prepared in the same manner as in Example 1.

In the reaction mixture in which propylene was recovered, the conversion of propylene was 77.1%, the selectivity of propylene to isopropyl alcohol was 99.0%, and the concentration of isopropyl alcohol was 9.0%.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.3 ppm of 1-propanol and 4 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentration of 4-methyl-2-pentanol as an impurity was 37 ppb, the concentration of 2-methyl-3-pentanone was 35 ppb and the concentration of 4-methyl-2-pentanone was 36 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

In Comparative Example 1, the isopropyl alcohol concentration in the reaction mixture was 1.1 to 1.5 times higher than in Examples 1 to 4, and the yield was increased. However, the concentration of the high boiling point compound in the resulting isopropyl alcohol exceeded 20 ppb And the purity was lower than in Examples 1 to 4.

&Lt; Comparative Example 2 &

[Production of isopropyl alcohol]

Except that the supply amount of water was 9.2 kg / h (the density was 920 kg / m ^3, therefore, it was 10 L / h), the amount of propylene supplied was 0.6 kg / h, and the residence time of water in the reactor was 60 minutes. In the same manner as in Example 1, isopropyl alcohol was produced.

In the reaction mixture in which propylene was recovered, the conversion of propylene was 88.8%, the selectivity to propylene for isopropyl alcohol was 98.3%, and the concentration of isopropyl alcohol was 8.2%.

[Analysis of impurities in isopropyl alcohol]

The obtained isopropyl alcohol was analyzed by GC-MS, and impurities contained in isopropyl alcohol were quantified. As a result, the obtained isopropyl alcohol contained 0.5 ppm of 1-propanol and 4 ppm of tertiary butanol.

Further, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described method (method of measuring high boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with longer holding time than isopropyl alcohol I did. Therefore, the concentration of the high boiling point compound having 5 to 30 carbon atoms was evaluated to be 500 ppb or less.

Then, the high boiling point compound in isopropyl alcohol concentrated according to the above-mentioned concentration method was analyzed by GC-MS using the method of [determination method of high boiling point compounds (qualitative analysis)] described above. Further, in order to perform a more detailed quantitative measurement on the peak detected by the qualitative analysis, GC-MS was used in the above-mentioned method of measuring a high boiling point compound (quantitative analysis) using isopropyl alcohol which was not concentrated Respectively. As a result, the concentration of 4-methyl-2-pentanol as an impurity was 45 ppb, the concentration of 2-methyl-3-pentanone was 41 ppb and the concentration of 4-methyl-2-pentanone was 50 ppb.

On the other hand, the obtained isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring low boiling point compounds (qualitative analysis)], and as a result, no peak was detected in a region with shorter holding time than isopropyl alcohol I did. Therefore, the concentration of the low boiling point compound was evaluated to be not more than 5000 ppb.

Then, the non-condensed isopropyl alcohol was analyzed by GC-MS using the above-described [method for measuring a low boiling point compound (quantitative analysis)]. As a result, the concentration of acetaldehyde was 0.5 ppm, the concentration of acetone was 0.2 ppm, and the concentration of propionaldehyde was 1.0 ppm.

In Comparative Example 2, the concentration of isopropyl alcohol in the reaction mixture was comparable to that in Examples 1 to 4, and the yield was maintained. However, the concentration of the high boiling point compound in the obtained isopropyl alcohol exceeded 20 ppb And the purity was lower than in Examples 1 to 4.

Reaction temperature [캜] Reaction pressure [atm] Supply ratio
Water [kg / hr] / propylene [kg / hr] Water stay time [min] pH Raw propylene Propylene [%] Propane [ppm] Ethane [ppm] Butene [ppm] Pentene [ppm] Hexene [ppm] Example 1 280 250 15 30 3 96 39972 20 8 0.1 or less 0.1 or less Example 2 280 250 15 40 3 96 39972 20 8 0.1 or less 0.1 or less Example 3 280 250 15 30 3 98 19956 40 4 0.1 or less 0.1 or less Example 4 280 250 20 30 3 96 39972 20 8 0.1 or less 0.1 or less Comparative Example 1 280 250 12 30 3 96 39972 20 8 0.1 or less 0.1 or less Comparative Example 2 280 250 15 60 3 96 39972 20 8 0.1 or less 0.1 or less

Propylene conversion rate [%] 2-propanol selectivity [%] Concentration of 2-propanol in the reaction mixture [%] Analysis results of 2-propanol Low boiling point compound High boiling point compound 1-propanol [ppm] Tertiary butanol [ppm] Acetaldehyde [ppm] Acetone [ppm] Propionaldehyde [ppm] 4-methyl-2-pentanol [ppb] 2-methyl-3-pentanone [ppb] 4-methyl-2-pentanone [ppb] Example 1 84.0 99.2 7.8 0.3 4 0.5 0.2 One 20 or less 20 or less 20 or less Example 2 86.4 98.9 8.0 0.4 4 0.5 0.2 One 20 or less 20 or less 20 or less Example 3 84.3 99.1 8.0 0.3 2 0.5 0.2 One 20 or less 20 or less 20 or less Example 4 86.2 99.2 6.0 0.2 4 0.5 0.2 One 20 or less 20 or less 20 or less Comparative Example 1 77.1 99.0 9.0 0.3 4 0.5 0.2 One 37 35 36 Comparative Example 2 88.8 98.3 8.2 0.5 4 0.5 0.2 One 45 41 50

The disclosure of Japanese application 2016-120761 filed on June 14, 2016 is incorporated herein by reference in its entirety.

Claims (5)

A process for producing isopropyl alcohol, wherein isopropyl alcohol is produced by directly hydrating propylene with water,
Propylene and water having a pH of 2.5 to 4.5 into a reactor;
A reaction step of reacting propylene with water in the reactor;
A recovery step of recovering propylene from the reaction mixture obtained in the reaction step;
A first distillation step of removing a low boiling point compound having a boiling point lower than isopropyl alcohol from the reaction mixture in which the propylene is recovered in the recovery step; And
And a second distillation step of removing water from the reaction mixture from which the low boiling point compound has been removed in the first distillation step to obtain isopropyl alcohol,
Wherein the ratio of propylene and water in the reactor is 1300 to 2100 parts by mass of water relative to 100 parts by mass of propylene and the residence time of water in the reactor is more than 20 minutes and less than 50 minutes.
The method according to claim 1,
A process for producing isopropyl alcohol wherein propylene having a purity of 98% by mass or more is used as a starting material in the raw material supplying step.
Isopropyl alcohol having a concentration of 4-methyl-2-pentanol, 2-methyl-3-pentanone and 4-methyl-2-pentanone as impurities both being 20 ppb or less by mass.
The method of claim 3,
Methyl-2-pentanone, 3-dimethyl-2-butanol, 2,3-dimethyl-2-butanol, Pentanol, 2-methyl-3-pentanol, 1-hexanol, 2-hexanol, 3-hexanol, Butanol, 2-ethyl-1-pentanol, 2-methyl-1-pentanol, 3-methyl- Diol, and isopropyl alcohol in which the concentration of 2,3-dimethyl-2,3-butanediol is not more than 20 ppb on a mass basis.
The method according to claim 3 or 4,
Wherein the concentration of the high boiling point compound as an impurity having a boiling point higher than that of isopropyl alcohol and having a carbon number of 5 to 30 is 500 ppb or less on a mass basis.

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