JPH0129776B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing isopropyl alcohol by directly hydrating propylene in an aqueous solution of a specified heteropolyacid. Specifically, by hydrating propylene under high temperature and pressure in an aqueous solution containing phosphovanadomolybdic acid, phosphomanganese molybdic acid, or a soluble salt thereof, corrosion of equipment materials is particularly inhibited, and isopropyl alcohol Relating to a method of manufacturing. Conventionally, in the direct hydration method of olefins, solid catalysts such as metal oxides, catalysts with silicotungsten or phosphoric acid supported on inert carriers, liquid catalysts with mineral acids such as sulfuric acid, and ion exchange catalysts have been used. It is being However, each of these catalysts has had problems, particularly in terms of industrial hydration activity and corrosion of mechanical strength device materials. Therefore, the present applicant has filed the patent application No. 50-35051,
As described in Publication No. 35052, a precipitate is produced by carrying out a hydration reaction of olefin under conditions of high temperature and pressure using a solution catalyst such as phosphomolybdic acid at a dilute concentration and a hydrogen ion concentration in a relatively small range. production, corrosion of equipment, and side reactions.
We have proposed a stable olefin hydration method and have already implemented it industrially. On the other hand, Special Public Interest Publication 51-13711
Publications list various heteropolyacids, ranging from 10 to 70
A method is disclosed in which olefins are hydrated at a practically sufficient reaction rate even at a high concentration (wt%) aqueous solution at a low temperature of 100 to 170°C, and alcohol is obtained with high selectivity. It is also stated that corrosion of the material is hardly a problem. However, in actual industrial manufacturing equipment,
Corrosion of equipment materials generally needs to be suppressed as much as possible. Therefore, when industrially producing alcohol by hydrating olefin using a solution catalyst of a heteropolyacid as described above, the process is also carried out using a low concentration aqueous solution of the heteropolyacid under high temperature and high pressure conditions. It is preferable that Further, in the method of producing isopropyl alcohol by hydrating propylene with a low concentration aqueous solution of a heteropolyacid under conditions of high temperature and high pressure, it is desirable to further suppress corrosion of equipment materials. In view of the above problems, the present inventors further conducted research on the hydration reaction of propylene under high temperature and high pressure using low concentration aqueous solutions of various heteropolyacids. As a result, it was discovered that when a specified heteropolyacid among various types of heteropolyacids is used, corrosion of device materials is significantly suppressed, and the present invention has been provided. That is, the present invention provides at least one of phosphovanadomolybdic acid, phosphomanganese molybdic acid, or a soluble salt thereof in an amount of 0.1 to 10
g/dissolved aqueous solution and propylene 180-350
This is a method for producing alcohol, which is characterized in that the alcohol is brought into contact at a temperature of .degree. According to the present invention, Japanese Patent Publication No. 50-35051, 50-35052
Similar to the method using a solution catalyst such as tungstic silicoic acid described in the publication, isopropyl alcohol can be obtained in good yield by hydrating propylene. In addition, from tests of corrosion rate over time on stainless steel using catalyst aqueous solutions of various heteropolyacids in Examples and Comparative Examples described later, it was found that when using the phosphovanadomolybdic acid and phosphomanganese molybdic acid of the present invention, 50−
It is recognized that the corrosion rate, especially at the initial stage, can be significantly reduced compared to silicotungstic acid, phosphotungstic acid, etc. described in Publications No. 35051 and 50-35052. Therefore, in the method of the present invention, it is possible to use ordinary stainless steel as the equipment material, and it is expected that corrosion will be prevented more than in the conventional method, and a decrease in catalytic activity due to corrosion can be avoided. Phosphovanadomolybdic acid, phosphomanganese molybdic acid, or a soluble salt thereof used as a catalyst component in the present invention has the general formula H _3+X [PMo _12-X V _X O ₄₀ ]·nH ₂ O, H _3+X [PMo Examples include _12-X Mn _X O ₄₀ ]・nH ₂ O. In order to industrially produce alcohol in good yield by the method of the present invention, taking into consideration corrosion prevention of equipment, the concentration of the above-mentioned catalyst component in an aqueous solution must be 0.1 to 10, preferably 0.5 to 5.
g/ is essential. i.e. 0.1
At concentrations below 10 g/g/g/g, the hydration reaction of propylene is not sufficiently achieved and isopropylene alcohol cannot be produced in good yield, while at concentrations above 10 g/g/g/g/g/g/g/g/l or higher, there is almost no difference in hydration activity, and conversely, the equipment materials are It is impractical due to its increased tendency to corrode. Further, in the present invention, it is also important to maintain the hydrogen ion concentration (PH) in the aqueous solution together with the above catalyst components at 2.0 to 4.5, preferably 2.5 to 4.0.
That is, as the hydrogen ion concentration increases, the hydration activity of the olefin can be increased, but since the decomposition rate of the catalyst components increases, long-term catalyst activity cannot be maintained, and there is a drawback that side reactions and equipment corrosion are promoted.
The hydrogen ion concentration (PH) of such a catalyst aqueous solution can be adjusted by using a basic substance soluble in the aqueous solution in which the above-mentioned catalyst components are dissolved, such as NaOH KOH, Ca(CH) ₂ ,
It is effective to add metal oxides such as MgO, metal oxides or ammonium hydroxide, or organic bases that do not decompose catalyst components and do not generate inert substances. Furthermore, in the method of the present invention, the reaction temperature is preferably 180 to 350°C as the propylene hydration condition.
It is extremely important to maintain the temperature between 200 and 300°C. The reaction pressure may be higher than the saturated vapor pressure at the above-mentioned reaction temperature, that is, higher than the pressure at which the liquid state can be maintained.The higher the pressure, the more advantageously alcohol can be produced, but in general, 100 to 500 kg/cm ² is suitable. As the apparatus used in the present invention, any known reaction apparatus for liquid phase direct hydration, for example, batchwise or continuous, can be employed without any restriction. In particular, when a continuous system is adopted, an absorption tower is generally used as the reaction device to efficiently bring the aqueous catalyst solution and propylene into contact with each other in parallel or countercurrent flow, and after distilling and separating the alcohol from the reaction liquid discharged from the reaction tower. , a method in which the residual liquid is circulated through the reaction tower is suitable. Hereinafter, the effects of the present invention will be illustrated by examples. Example 1 A predetermined amount of a heteropolyacid such as phosphovanadomolybdic acid was dissolved in ion-exchanged water, and 150 ml of the aqueous solution whose pH value was adjusted with the added alkali shown in Table 1 was placed in a silver-lined autoclave with an internal volume of 300 ml. Table 1 shows the reaction results under various conditions in which propylene was injected while heating, and when a predetermined temperature was reached, the injection of propylene was stopped and the reaction was allowed to proceed for a predetermined period of time. For comparison, propylene was reacted with 150 ml of lyremolybdic acid aqueous solution adjusted to pH 2.9 under the same reaction conditions as No. 2 of Example 1, and the concentration of the obtained isopropyl alcohol (IPA) was
At 11.0wt%, the selectivity was 98%.

[Table] Example 2 Two types of stainless steel shown in Table 2 (15 mm (width) x 70 mm (length) x 2 mm (thickness) A test piece with the shape of
An aqueous catalyst solution containing the heteropolyacid shown in Table 3 was supplied from the top at a rate of 3 Kg/Hr per reaction volume, and propylene was also supplied from the bottom at a rate of 0.2 Kg/Hr.
While blowing at the rate of Hr, 300℃, 200Kg/
A continuous hydration reaction was carried out under the reaction conditions of cm ² G, and Table 3
The corrosion weight loss after the elapse of time shown in was determined, and the corrosion rate was calculated from this. The results are summarized in Table 3.

【table】

[Table] Example 3 Material B shown in Table-2 (shape: 15 mm (width) x 50 mm
Example 1 except that (length) x 2 mm (thickness)) was placed in a silver-plated autoclave and the reaction time was 24 hours.
The hydration reaction of propylene was carried out in exactly the same manner as in No. 2. The results of measuring the pH of the aqueous solution after the completion of the reaction are shown in Table 4.

【table】

Claims (1)

[Claims] 1. Bringing an aqueous solution containing 0.1 to 10 g/dissolved of phosphovanadomolybdic acid, phosphomanganese molybdic acid, or at least one of their soluble salts into contact with propylene at a temperature of 180 to 350°C. Characteristic method for producing isopropyl alcohol. 2. The manufacturing method according to claim 1, wherein the aqueous solution has a pH of 2.0 to 4.5.