JP2002121160A - Method for producing isopropyl alcohol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing isopropyl alcohol, comprising obtaining the isopropyl alcohol from acetone and hydrogen, by which the highly pure isopropyl alcohol can be produced using crude acetone, a process liquid of an acetone production process, without positively using highly purified acetone. SOLUTION: This method for producing the isopropyl alcohol, comprising reacting the acetone with the hydrogen, characterized in that the total amount of aldehydes, alcohols and ketones (excluding the acetone) in the acetone of raw material is <=0.3 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing isopropyl alcohol, and more particularly to a method for producing high-purity isopropyl alcohol by reacting acetone with hydrogen. Isopropyl alcohol is an important intermediate in organic synthesis and an industrially important solvent.

[0002]

2. Description of the Related Art Isopropyl alcohol is used as a general solvent, but is often used as a cleaning agent for IC substrates and a disinfectant, and high purity products are required. In general, products having a product purity of 99.9% by weight or more are commercially available. In particular, in a disinfectant solution or a cleaning agent for an IC substrate where a slight difference in odor is a problem, even a trace amount of impurities is used. It will have an adverse effect. Accordingly, it is necessary to minimize contamination of impurities such as alcohols and aldehydes such as methanol, ethanol and n-propanol.

As a method for producing isopropyl alcohol, an indirect hydration method in which propylene is esterified with concentrated sulfuric acid followed by hydrolysis and a direct hydration method in which propylene is directly hydrated using a heteropoly acid or the like as a catalyst are widely used. In this case, there is a problem that the apparatus is corroded by the sulfuric acid or heteropolyacid as a catalyst. Further, in these propylene hydration methods, n-propyl alcohol, ter-butyl alcohol, 2-methyl-2-pentene, 2-methyl-
Various impurities such as 1-pentene and diisopropyl ether are produced as by-products. For this reason, despite the fact that distillation and purification are carried out with a large amount of energy in many distillation columns having many stages, n-propyl Many impurities such as alcohol and t-butyl alcohol are mixed into the product, causing the purity to deteriorate and the odor to deteriorate. Above all, for applications in the field of electronic materials such as cleaning agents for IC substrates, they are manufactured by distillation by further increasing the reflux ratio or increasing the number of distillation stages.

[0004] As a method for producing isopropyl alcohol, a method of hydrogenating the carbonyl group of acetone has been known for a long time. For example, lithium aluminum hydride,
This is a reduction method using a reagent such as sodium borohydride or a catalytic reduction method using hydrogen gas.

As a method using hydrogen gas, for example,
A method using bulk Raney nickel as a catalyst (Japanese Patent Application Laid-Open No. 3-141235), a method using a trickle bed system comprising three phases of gas, liquid and solid (Japanese Patent Application Laid-Open No. 2-27)
No. 0829), and a method of circulating a part of the reaction mixture to improve the reaction yield (Japanese Patent Application Laid-Open No. H3-133941).

However, all of these methods provide a method for improving the reaction results. Among them, JP-A-3-141235 and JP-A-3-133941 disclose that the raw material acetone contains water. It is described that aldehydes such as acetaldehyde, alcohols such as methanol and ethanol, and furthermore, cumene and aromatic hydrocarbons such as α-methylstyrene may be included. No mention is made of quality improvement.

[0007]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to prepare an isopropyl alcohol by reacting acetone with hydrogen without using a purified high-purity acetone. It is an object of the present invention to provide a method for producing high-purity isopropyl alcohol using crude acetone as a process liquid as a raw material.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on impurities in the raw material acetone in order to solve the above-mentioned problems. As a result, aldehydes which are contained in a large amount in the acetone production process and are difficult to separate from acetone are found. When using crude acetone as a raw material before sufficiently separating and removing alcohols and ketones, by defining the content of these impurities, high-quality isopropyl alcohol can be produced without adversely affecting the quality of the produced isopropyl alcohol. The inventors have found that isopropyl alcohol can be obtained, and have completed the present invention. That is, the present invention relates to a method for producing isopropyl alcohol by reacting acetone and hydrogen, wherein the total of aldehydes, alcohols and ketones (excluding acetone) in the raw material acetone is 0.3% by weight.
A method for producing isopropyl alcohol, characterized in that:

[0009]

DETAILED DESCRIPTION OF THE INVENTION Isopropyl alcohol is generally purified by distillation to obtain a product. As an example of using acetone and hydrogen as raw materials, first, unreacted hydrogen and acetone are separated from the obtained reaction mixture. Subsequently, high-purity isopropyl alcohol can be obtained by removing water and separating a near-boiling compound or a high-boiling compound. The high-purity isopropyl alcohol referred to in the present invention has a purity of 99.9% or more.

As the raw material acetone used in the present invention, one produced by a by-product of a cumene phenol plant or a direct oxidation method of propylene is used. But,
In these processes, low-boiling alcohols, aldehydes, and ketones such as methanol, acetaldehyde, propioaldehyde, and methyl ethyl ketone are by-produced, and are impurities to be noted in purification with acetone.

[0011] For example, in the case of the cumene method, cumene hydroperoxide obtained by oxidizing cumene is acid-decomposed to produce phenol and acetone. The synthesis solution thus obtained contains various impurities. In the case of purifying acetone, for example, it is sequentially purified in several distillation columns equipped with 30 to 60 trays to obtain a product. As an example, the following method is used. First, a high boiling component mainly composed of phenol or cumene is separated by distillation in a crude acetone tower. Next, low boiling substances such as methanol and acetaldehyde are removed in a low boiling separation column. Subsequently, high-purity acetone can be obtained only by separating a substance having a boiling point higher than that of acetone in the acetone purification tower. In the separation of the aldehyde, there is a case in which an alkali such as caustic soda is supplied to the distillation column to make it easier to separate by increasing the boiling point. In this way, the commercial product acetone is produced, but requires a lot of equipment and a lot of energy.

Therefore, the crude acetone used in the present invention can be used as a process liquid in the above-mentioned acetone production process.
For example, in the above-mentioned cumene phenol process, use of crude acetone obtained from a crude acetone column or a low-boiling separation column in a previous step of an acetone purification column may be considered. Incidentally, each distillation column of the acetone purification system consumes a large amount of energy because the reflux ratio is as high as 2 to 6. Therefore, the total amount of the aldehydes, alcohols, and ketones (excluding acetone) in the crude acetone is reduced to 0.3% by weight or less by withdrawing from the middle column or reducing the reflux ratio of the distillation column. By using the crude acetone adjusted as described above, a large amount of energy can be saved.

Here, aldehydes are particularly those having 1 carbon atom.
For example, formaldehyde, acetaldehyde,
Examples include propionaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde and the like. When these aldehydes are present, they are reduced in the hydrogenation reaction to form the corresponding alcohol having 1 to 5 carbon atoms.

Alcohols include those having 1 to 5 carbon atoms excluding isopropyl alcohol, such as methanol,
Ethanol, n-propanol, n-butanol, se
Examples thereof include c-butanol, iso-butanol, and 2-pentanol. These alcohols have a boiling point close to that of isopropyl alcohol, and thus are difficult to separate by distillation.

Further, ketones include those having 4 and 5 carbon atoms, such as methyl ethyl ketone and diethyl ketone, and like the aldehydes, are reduced by hydrogenation to form the corresponding alcohols.

In any case, these aldehydes and ketones are sometimes difficult to separate as they are, but since they are converted into corresponding alcohols by a synthesis reaction, separation from isopropyl alcohol becomes difficult. Therefore, prior to the reaction with alcohols, it is desirable to remove them so that the total amount is 0.3% by weight or less.

The purity of the hydrogen used in the present invention is not particularly limited, but is generally preferably 90% by volume or more. As the contained impurities, they can be used without any problem as long as the reaction of nitrogen, argon, methane, ethane or the like is not seriously affected.

Examples of the catalyst used in the hydrogenation reaction of the present invention include noble metal catalysts such as Cu-Cr based oxide catalysts, Raney Ni catalysts, Raney Cu catalysts, Pt, Pd and Ru. What has been applied can be applied as it is.

Examples of the reactor include a packed bed reactor, a trickle bed reactor, a multitubular reactor, a moving bed reactor, a suspended bubble column reactor, and a stirred tank suspension reactor.

The reaction temperature and the reaction pressure are not particularly limited, but generally differ depending on the atmosphere in the reactor.
MPa-G, 60-200 ° C, 1M in gas phase reaction
It is performed under the condition of Pa-G or less.

According to the method of the present invention using acetone and hydrogen as the raw materials under the above-mentioned conditions, the amount and number of by-produced impurities are greatly reduced, and in particular, acetone having a purity of 99.9% by weight or more, That is, the carbon number other than isopropyl alcohol is 1
0.1 to 5% by weight of the alcohol having 1 to 5 carbon atoms, the acetaldehyde having 1 to 5 carbon atoms and the ketone having 4 and 5 carbon atoms.
When the following acetone is used, the number of impurities contained in the product is greatly reduced and the odor is significantly improved.

[0022]

The present invention will be described in more detail with reference to the following examples. The composition analysis described in the examples was performed by the following method.

The composition was analyzed by GC-14A manufactured by Shimadzu Corporation.
(Detector: FID, column: DB-WAX) Gas chromatography was used to measure He as a carrier gas. The water content was measured with a Karl Fischer moisture meter.

Example 1 [Preparation of catalyst] In the middle of a stainless steel reactor having an inner diameter of 50 mm and a length of 100 mm, a massive nickel aluminum alloy (R-20L, manufactured by Nikko Rica, particle size: 4-5 mm, Ni
/ Al weight ratio: 50/50) 200 g (100 ml)
To form a fixed catalyst layer, and the reactor was filled with water. Next, a 3000 ml water tank and the lower part of the reactor were connected via a liquid sending pump. A path was provided for returning the liquid passed through the reactor from the upper part of the reactor to the water tank. Next, while driving the liquid feed pump and circulating water in the reactor at a flow rate of 0.25 L / min, a separately prepared 40% aqueous sodium hydroxide solution was dropped into the water tank, and the alkaline aqueous solution was discharged. The reaction system was circulated.

The Raney nickel catalyst was developed by circulation of the alkaline aqueous solution. At this time, the reaction heat was generated with the development of the catalyst, and the internal temperature of the reactor increased. Therefore, the dropping rate of the aqueous sodium hydroxide solution was adjusted so that the internal temperature did not exceed 50 ° C. The aqueous sodium hydroxide solution was added dropwise in an amount corresponding to 270 g of sodium hydroxide in total. After the completion of the dropwise addition, the circulation of the alkaline aqueous solution was continued, and the developing treatment was performed for a total of 20 hours. After the completion of the developing process, pure water was flowed into the reactor to wash the fixed catalyst layer. The washing was continued until the pH of the discharged washing liquid became 11 or less.

After that, the alkaline aqueous solution and the washing solution were all collected, and the amount of aluminum eluted therein was measured by a chelate titration method. The expansion ratio = aluminum elution amount / aluminum amount in nickel-aluminum alloy ×
According to 100, the expansion rate of the obtained Raney nickel catalyst was determined. As a result, it was found that a Raney nickel catalyst having an expansion rate of 54% was adjusted.

[Synthesis of isopropyl alcohol] Inner diameter 2
A 5.4 mm, 500 mm long vertical stainless steel reactor was filled with distilled water. Next, 25 mL of the Raney nickel catalyst obtained by adjusting the above catalyst was filled in the middle of the reactor, and water was extracted while keeping the inside of the reactor under a nitrogen atmosphere.

Next, isopropyl alcohol was supplied from the upper part of the reactor, and water remaining in the reactor was replaced with isopropyl alcohol. Subsequently, the reactor was heated while continuously supplying isopropyl alcohol and hydrogen from the upper portion of the reactor. When the internal temperature of the reactor reached 50 ° C., acetone was supplied instead of isopropyl alcohol to start the hydrogenation reaction of acetone. Here, the purity of the acetone used was 99.9% by weight, 0.02% by weight of an alcohol having 1 to 5 carbon atoms (hereinafter referred to as C1 to C5) other than isopropyl alcohol, and 0% of acetaldehyde of C1 to C5. The ketone containing 0.011% by weight and having 4 and 5 carbon atoms (hereinafter referred to as C4 & C5) contained impurities such as not detected. The feed rates of acetone and hydrogen were 40 g / hr and 37 L / hr, respectively, and the reaction pressure was 2
It adjusted so that it might be set to MPa-G. The reaction temperature was adjusted so that the reactor temperature was cooled to 100 ° C. to remove the reaction heat.

As the reaction proceeds, a gas-liquid mixture comprising a liquid reaction product and hydrogen gas is discharged from the lower part of the reactor. This is subjected to gas-liquid separation to obtain a liquid reaction product. The supply of acetone and hydrogen was continued, and 10 hours after the reaction was stabilized, collection of a liquid reaction product was started. When the composition of the collected reaction product was analyzed by gas chromatography, 0.8% by weight of unreacted acetone was present and the concentration of isopropyl alcohol was 99.08% by weight.
Met. In addition, C1 excluding isopropyl alcohol
Alcohol of C5 0.02% by weight, aldehydes of C1 to C5 and ketones of C4 & C5 were not detected, presumably because they were both converted to alcohols. The composition of the raw material acetone is shown in Table 1, and the composition of the reaction product is shown in Table 2.

[Distillation Purification of Reaction Product] The reaction product produced by the above method was purified by distillation in the following manner. That is,
Batch distillation was performed under a reflux ratio of 4 in a 1.5-inch distillation column filled with 0.4 m of Helipack # 2 (manufactured by Tokyo Specialty Wire Mesh). As a result of mixing the fractions having a distilling rate of 30 to 90% from the top of the column and analyzing the mixture by gas chromatography, the purity of isopropyl alcohol was 99.99% by weight. The content was as small as 0.001% by weight. Also, C1 to C
No aldehyde of 5 and ketone of C4 & C5 were detected. Table 3 shows the analysis results of the purified isopropyl alcohol. The obtained isopropyl alcohol showed a small number of impurities detected on gas chromatography and also showed a better odor than the conventional product obtained by the current hydration method.

The reflux ratio and the distillation rate of the distillation column in Example 1 are defined as follows. Reflux ratio = (weight of liquid refluxed to distillation column out of vapor condensate at the top / weight of liquid extracted outside system) Distillation rate (%) = fraction extracted from system top of distillation column to outside Integrated amount / weight of liquid charged in distillation column x 10
Indicated by 0.

Example 2 Using crude acetone obtained as a by-product of a cumene phenol plant as a raw material, its purity was 97.68% by weight, C1
0.031% by weight of C5 to C5 alcohol, 0.037% by weight of C1 to C5 aldehyde, 0.04% of C4 & C5 ketone
The same procedure as in Example 1 was carried out except that a substance containing 5% by weight and 2.202% by weight of other impurities was used. Table 1 shows the results
As shown in FIGS. 3 to 3, the unreacted acetone slightly increased to 0.9% by weight, but the purified isopropyl alcohol had a purity of 99.97% by weight, and the content of alcohols C1 to C5 excluding isopropyl alcohol was 0.018% by weight, C1-C5 aldehyde and C4 & C5 ketone were not detected. In addition, the odor showed good results comparable to products obtained by the current hydration method.

Example 3 The raw material acetone had a purity of 97.49% by weight and C1 to C1.
C5 alcohol 0.053% by weight, C1 to C5 aldehyde 0.102% by weight, C4 & C5 ketone 0.11
The procedure was performed in the same manner as in Example 2 except that crude acetone containing 2.245% by weight and 2.245% by weight of other impurities was used. As shown in Tables 1 to 3, the unreacted acetone slightly increased to 1.0% by weight, but the purity of the purified isopropyl alcohol was 99.93% by weight. 0.061 alcohol content
Weight%, C1-C5 aldehydes and C4 & C5 ketones were not detected. In addition, the odor showed good results comparable to products obtained by the current hydration method.

Comparative Example 1 Raw material acetone was 97.21% by weight in purity, 0.055% by weight of C1-C5 alcohol, 0.37% by weight of C1-C5 aldehyde, 0.12% by weight of C4 & C5 ketone,
Others Example 2 was repeated except that acetone containing 2.245% by weight of impurities was used. The results are shown in Tables 1 to 3.
As shown in the figure, the unreacted acetone increased to 1.20% by weight, and the purity of the purified isopropyl alcohol was 9%.
9.74% by weight, current product (99.9% by weight or more)
It became lower purity. As impurities, 0.25% by weight of C1-C5 alcohol except isopropyl alcohol, C1-C5 aldehyde and C4 & C5 ketone were not detected. In addition, the odor showed a more unpleasant odor than the product obtained by the current hydration method, and was out of specification.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

According to the present invention, the impurities contained in crude acetone, which is a process liquid of the acetone production process, as well as purified high-purity acetone are specified and the content thereof is specified. As a result, the energy required for the purification of the raw material acetone can be reduced, so that the production cost of isopropyl alcohol can be reduced, and high-purity isopropyl alcohol can be produced, which is industrially superior.

Claims (4)

[Claims] 1. A method for producing isopropyl alcohol by reacting acetone and hydrogen, wherein the total of aldehydes, alcohols and ketones (excluding acetone) in the raw material acetone is 0.3% by weight or less. A method for producing isopropyl alcohol. 2. The method according to claim 1, wherein the aldehyde is an aldehyde having 1 to 5 carbon atoms. 3. The method according to claim 1, wherein the alcohol is an alcohol having 1 to 5 carbon atoms. 4. The method according to claim 1, wherein the ketone is a ketone having 4 or 5 carbon atoms.