JPS6212729A - Production of isopropyl alcohol - Google Patents

Abstract

PURPOSE:To produce isopropyl alcohol useful as a raw material in improved yield, without producing by-products, by reacting acetone with hydrogen in the presence of a catalyst while controlling the pH of the catalyst, the water- content of the reaction system and the unreacted amount of acetone at a specific temperature to respective specific levels. CONSTITUTION:The objective compound is produced by reacting acetone with hydrogen in the presence of a Raney-Ni catalyst containing an alkali in an amount to give an aqueous solution of 7.0-8.2pH when the catalyst is immersed in water, in a reaction system having a water-content of <=5wt%, preferably <=1.0wt% at a reaction temperature of 100-160 deg.C, preferably 105-150 deg.C while controlling the amount of unreacted acetone to >=0.5wt%, preferably 2-15wt%. The unreacted amount of acetone is the acetone content in the reaction mixture discharged from the reactor, and can be controlled within the above range by keeping the reaction temperature within the above range and selecting the reaction time and the hydrogen pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing isopropyl alcohol, which is useful as various industrial raw materials and solvents, by reacting acetone and hydrogen.

[Conventional technology]

A conventional method for obtaining isopropyl alcohol by reducing acetone with hydrogen is described in, for example, Industrial Chemistry Magazine, Volume 54, Book 1, Page 27 (1952), using N1 as a catalyst.
- From Al(1:1) alloy by conventional method
j preparation, ta, nayuga 7. Aya F7 is hydrogenated using
: A method for obtaining isopropyl alcohol by adding is described. However, the yield of isopropyl alcohol shown in this document is 93.3%, and when considering industrialization of isopropyl alcohol production, it is necessary to further increase the yield. However, in conventionally known methods, when the addition rate of acetone is increased in an attempt to increase the yield of isopropyl alcohol, the amount of by-products such as diisopropyl ether, propane, ethane, and methane increases, which increases the amount of by-products in the reaction mixture. This becomes a problem when separating isopropyl alcohol from In addition, the above-mentioned literature describes that as a method for increasing the yield of isopropyl alcohol, adding water increases the yield as high as 98.7% and promotes hydrogenation. There are problems in adopting this method for the industrial production of isopropyl alcohol. This is because when separating isopropyl alcohol from the reaction mixture, this method is not economical since isopropyl alcohol and water form an azeotrope, making the separation process complicated and expensive.

[Problem that the invention seeks to solve]

The present inventors have recognized that the conventional method of hydrogenating acetone to obtain isopropyl alcohol in the presence of a Raney nickel catalyst has the above-mentioned problems. The inventors also found that when using Raney nickel for the reaction, Nt
- The amount of by-products of (MIBK) and methyl isobutyl carbinol (?11BC) may vary due to differences in catalyst preparation methods, including the development operation in which Affi is eluted from the Alt alloy with alkali and the catalyst washing operation after development. found that it increases. Against this background, the present inventors have developed a method for industrially producing isopropyl alcohol economically and efficiently by hydrogenating acetone with a high selectivity and with a small amount of the various by-products mentioned above. investigated.

[Means and actions for solving the problems] As a result, the inventors discovered that the above object could be achieved by employing the following method, and completed the present invention.

That is, according to the method of the present invention, when acetone is reacted with hydrogen in the presence of a Raney nickel catalyst to obtain isopropyl alcohol, the amount of alkali present in the catalyst is expressed as the pH value of the aqueous solution in which the catalyst is immersed. Using a catalyst in the range of 0 to 8.2, the moisture content of the reaction system is 5% by weight or less, the reaction temperature is 100 to 160°C, and the unreacted amount of acetone is 0.5% by weight or more. A method for producing isopropyl alcohol, which is characterized by carrying out the reaction, is provided.

The Raney nickel catalyst used in the present invention is a catalyst in which the amount of alkali present in the catalyst is in the range of 7.0 to 8.2, expressed as the pH value of the solution in water in which the catalyst is immersed. The pH value of the aqueous solution employed in the present invention, which is considered to correspond to the amount of alkali present in the catalyst in this case, is a value determined by the following method. That is, N1-A I! Alloy A by alkali
A method for preparing a Raney nickel catalyst by carrying out a normal development operation to elute 1, then washing it with water, and after washing, optionally treating the catalyst with a solution having a pH value within the above range. About 1% of the catalyst after this washing or treatment in
0g (wet state) to 501 parts water! Soak at room temperature for usually 1 hour.
This is the value obtained by measuring the pH of the aqueous solution after it has been left standing with a pH meter using an electrode method. In the present invention, the pH
If the pH value is less than 7.0, it means that the medium in which Raney nickel is stored is acidic, and the surface is altered during storage, making it impossible to maintain the desired activity. If it exceeds 8.2, it is not preferable because by-products such as old BK and MIBC will be produced and their amounts will increase when such a catalyst is used for the reaction. In the present invention, as the Raney nickel to be subjected to the reaction, a Raney nickel that has been subjected to the final washing operation after the development described above, and which has been treated by immersing the Raney nickel in an alkali-containing aqueous solution as necessary, can be used as a catalyst. In this case, the Raney nickel after washing is immersed in an alkali-containing aqueous solution at an appropriate temperature for usually 1 hour or more. Aqueous solutions are used. In this case, alkali-containing aqueous solutions include Li5K, RbsCs hydroxide aqueous solution, Be
, Mg, , Ca5Sr, Ba, and other alkaline earth metal hydroxides.

In the present invention, when producing isopropyl alcohol by reacting acetone and hydrogen, the water content of the reaction system is 5.0.
The reaction is carried out in such a way that the amount is less than 1.0% by weight, preferably less than 1.0% by weight. The water content in this case is the content of water in the reaction mixture present in the reaction system, and if the water content exceeds 5% by weight, high purity isopropyl alcohol that does not contain water is removed from the reaction mixture. It is not preferable because it requires a complicated process to separate and is expensive. In the present invention, in order to bring the water content of the reaction system into the above range, the acetone used as a raw material has a water content of 5.
It is preferable that the amount is less than % by weight.

When the water content of the reaction system is reduced in this way, it is advantageous because the dehydration operation can be omitted in the operation of separating and purifying isopropyl alcohol from the reaction mixture.

In the present invention, the reaction temperature of acetone and hydrogen is 10
It is carried out at a temperature of 0 to 160°C, preferably 105 to 150°C. If the reaction temperature exceeds 160°C, by-products such as diisopropyl ether, propane, ethane, methane, etc. will be produced and their amounts will increase, which is not preferable. Furthermore, if the reaction temperature is less than 100° C., the reaction rate decreases, and in order to increase the yield of isopropyl alcohol, the reaction time must be significantly lengthened, and in this case, the amount of by-products also increases, which is not preferable.

In the present invention, the reaction between acetone and hydrogen can be carried out by a batch method, a flow method, or the like. In the case of the distribution method, unreacted acetone is recycled to the reaction system to carry out the reaction.

In the present invention, in the reaction between acetone and hydrogen, the amount of unreacted acetone is 0.5% by weight or more, preferably 2 to 15% by weight.
This is done as follows. In this case, the unreacted amount of acetone is the acetone content ratio in the reaction mixture coming out of the reactor. In order to keep the unreacted amount of acetone within the above range, it can be carried out by adjusting the reaction temperature within the above range and, for example, appropriately selecting the reaction time, hydrogen pressure, etc.

In the case of a liquid phase method using a batch method, the reaction time is usually about 10 minutes to 1.5 hours, and the hydrogen partial pressure is usually about 5 to 40 kg/colG. If the reaction amount is as low as 0.5% by weight or less and the conversion rate of acetone is increased, this is not preferable because by-products such as diisopropyl ether and )-ropane described above will increase.

In the present invention, when a batch method is used, the amount of acetone, hydrogen and catalyst used is usually 1 to 30 parts by weight per 100 parts by weight of acetone, and the amount of hydrogen used is 1 to 30 parts by weight per 100 parts by weight of acetone. It is usually 0.8 to 10 times the molar amount.

In the present invention, highly pure isopropyl alcohol can be obtained by subjecting the reaction mixture to a commonly known distillation method and, if necessary, dehydration operation after completion of the reaction.

〔Effect of the invention〕

By employing the method of the present invention, highly pure isopropyl alcohol containing almost no water can be efficiently produced with a high selectivity and a small amount of reaction by-products.

[Example] Hereinafter, the method of the present invention will be specifically explained with reference to Examples.

Example 1 (Reaction) Acetone 66.4i1t%, isopropyl alcohol (
IPA) 33.3 wt%, moisture 0.3 wt% acetone solution (300 ml) and Raney nickel (8 volatile, thoroughly washed with water to adjust pH to 7.6, then replaced with IPA to make a state substantially free of water) 15.7 g (15.7 g of the ingested material was dried in nitrogen) was added to the autoclave No. 11, and the autoclave was sealed with hydrogen at room temperature under normal pressure.
Heated to 50°C. After reaching 150°C, hydrogen was injected to make the total pressure 26 kg/cJ G. At the start of stirring, hydrogen was supplied through a pressure control valve to maintain this pressure, and during this period the reaction temperature was maintained at 150°C.

The reaction was stopped after 30 minutes. Product composition is acetone
10.7%, IPA 99.0%, water 0.3w
It was t%.

After settling the catalyst, 200 mf of the reaction liquid was extracted, and 200 mf of acetone with a water content of 0.3% was added to the precipitated and separated catalyst.
d and the reaction was repeated 14 times in the same manner. Throughout the series of reactions, no diisopropyl ether was detected and no decrease in catalyst activity was observed.

The composition of the product thus obtained was 0.0% acetone.
8wt%, IPA 98.9i1t%, water 0.3%1t
%.

1000 parts of the reaction product was charged into a 50-stage Oldershaw type distillation column, and atmospheric pressure batch distillation was carried out under conditions of a reflux ratio of 2.0. When 75 parts were withdrawn, all unreacted acetone was recovered and was not detected in the remainder of the pot. (The water content of the remainder of the pot was 0.11 wt%.) Further distillation was performed to obtain 910 parts of IPA with a boiling point of 83°C.

Methyl isobutyl ketone and methyl isobutyl carbinol were not detected in this m IPA, and the water content was 0.11%.

Comparative Example 1 The reaction was repeated in the same manner as in Example 1 except that the reaction temperature was 175°C.

Product composition: 0.7% acetone, 16% isopropyne.
3%, ethane 0.8%, and propane 4.3%.

Comparative Example 2 The reaction was repeated in the same manner as in Example 1 at a reaction temperature of 130° C. so that the amount of unreacted acetone was 0.5% or less. The reaction time at this time was about 2 hours, and the building alcohol 98
．． 8%, water 0.5%, diisopropyl ether 0.6
%, and the amount of diisopropyl ether by-product increased.

Comparative Example 3 The pH of Raney nickel was adjusted to 9.5, and the reaction temperature was 1.
The first experiment of Example 1 was repeated except that the temperature was 20°C.

Product composition: 2.7% acetone, 9% isopropanol
6.5%, water 0.4%, methyl isobutyl ketone 0.1
%, methyl isobutyl carbinol 0.3%.

Claims (1)

[Claims] (1) In obtaining isopropyl alcohol by reacting acetone with hydrogen in the presence of a Raney-nickel catalyst,
Using a catalyst in which the amount of alkali present in the catalyst is in the range of 7.0 to 8.2 expressed as the pH value of the aqueous solution in which the catalyst is immersed, the water content of the reaction system is 5% by weight or less, and the reaction temperature is A method for producing isopropyl alcohol, characterized in that the reaction is carried out at a temperature in the range of 100 to 160°C such that the amount of unreacted acetone is 0.5% by weight or more.