JPH0448782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for synthesizing aluminum alkoxide from aluminum and isopropyl alcohol.

[Prior Art] It is widely known that aluminum alkoxide is used as a catalyst, but in recent years, its use as a raw material for high-purity alumina on an industrial scale or as a raw material for pharmaceuticals, paints, inks, etc. has also rapidly increased. It is growing. Many proposals have been made for methods for obtaining aluminum alkoxide on an industrial scale, but the main feature is the extremely high heat of reaction, said to be about 95 kcal per mole, generated when aluminum alkoxide is produced. The aim is to avoid the operational dangers that may have arisen.

The main methods to avoid this risk include limiting the amount of alcohol involved in the reaction by diluting the alcohol with non-reactive hydrocarbons that do not participate in the alkoxide synthesis, or reacting aluminum with liquid alcohol. A method of rolling aluminum foil into particles with irregular voids to suppress rapid reactions (Japanese Patent Application Laid-Open No. 57-35529), or synthesizing aluminum alkoxide by bringing alcohol vapor into contact with aluminum, Method for limiting the amount of alcohol vapor that comes into contact with aluminum (Special Publication No. 39-17265)
No.) etc.

[Problems to be Solved by the Invention] However, in the above method, the vapor pressure of the non-reactive hydrocarbon used for dilution during aluminum alkoxide distillation after aluminum alkoxide synthesis is lower than that of the synthesized aluminum alkoxide. Since the pressure is high compared to the vapor pressure, it is necessary to remove these hydrocarbons in advance, making the distillation operation complicated.
In particular, when the hydrocarbon used is difficult to dissolve in water, and when aluminum alkoxide is hydrolyzed and used as an alumina raw material, hydrocarbons that could not be removed during distillation may be hydrolyzed to produce alumina hydrate. If the alumina is separated and remains in the water, there is a possibility that the alumina raw material will be non-uniform. Therefore, during the distillation of alkoxides, great care must be taken to remove hydrocarbons, which is troublesome. At the same time, because this method limits the amount of alcohol involved in the reaction, the rate of alkoxide production is low, and if you want to obtain the same amount of synthesis per hour, you will have to use a larger synthesizer. There were some drawbacks as well.

Furthermore, the above method has the advantage of avoiding the uncontrollable state of production rate that tends to occur when aluminum powder with a large specific surface area is used, but when aluminum foil is granulated in large quantities on an industrial scale,
Depending on the storage conditions, the voids in the aluminum grains in the lower pile are crushed and the grain size tends to change, and there is a risk that the reaction rate will not be constant due to the variation in grain size.

Furthermore, in the above method, the rate of alkoxide production is greatly affected by the amount of alcohol vapor that comes into contact with the aluminum, so in order to prevent process operation interruptions, it is necessary to generate excess alcohol vapor, which requires energy. The drawback was that consumption was extremely large.

An object of the present invention is to provide a method for synthesizing aluminum alkoxide in which the distillation operation after synthesizing the alkoxide is simple and the alkoxide can be synthesized at a high and stable production rate with only a small amount of external energy consumed. It is in.

[Means for Solving the Problems] The present inventors have proposed that by actively utilizing the very high reaction heat generated when aluminum alkoxide is generated as energy for generating alcohol vapor in the above-mentioned method. , it is possible to save energy supplied from outside, and
In addition, aluminum alkoxide can be generated in liquid alcohol even when alcohol vapor is generated, and if aluminum powder with a large specific surface area is reacted with liquid alcohol under specific conditions, it can be done without relying on the above method. The present invention was completed by focusing on the fact that the generation of reaction heat can be controlled even when the reaction heat is generated.

That is, the configuration of the present invention will be explained based on FIG. 2 is vaporized, and the vaporized isopropyl alcohol is brought into contact with an aluminum lump 5 housed in a second reactor 4, which is provided in communication with the upper part of the first reactor 1, to form aluminum alkoxide. This is a method of synthesis.

Its characteristic structure is that when the isopropyl alcohol 2 begins to vaporize due to the heating of the heater 3, the heating amount of the heater 3 is reduced or the heating is stopped, and the aluminum Aluminum powder 8 is introduced into the first reactor 1 from the powder introduction part 7 at a ratio of 0.005 to 0.17 mol per mol of isopropyl alcohol in total to react with isopropyl alcohol 2, and the isopropyl alcohol 2 is vaporized by the heat of reaction. It's about doing.

The alcohol used in the present invention is isopropyl alcohol, which is relatively inexpensive and easily available, allows easy synthesis of aluminum alkoxide, and is easy to distill after synthesizing the alkoxide.

When aluminum is added to isopropyl alcohol, aluminum isopropoxide is synthesized using the following reaction formula.

The reaction heat generated by this synthesis is approximately 95 kcal per mole (204 g) of aluminum isopropoxide from the reaction of 1 mole (27 g) of aluminum and 3 moles (180 g) of isopropyl alcohol. The latent heat of vaporization per mole of isopropyl alcohol is
Since it has 9.57 kcal, it can evaporate 9.92 moles (about 600 g) of isopropyl alcohol.

That is, when 1 mole of aluminum isopropoxide is synthesized from 12.92 moles of isopropyl alcohol, which is 3 moles of isopropyl alcohol used in the reaction with 1 mole of aluminum and 9.92 moles of evaporated isopropyl alcohol, 9.92 moles of unreacted
Moles of isopropyl alcohol can be boiled. If this is converted into 1 mol of isopropyl alcohol, the amount of aluminum required for reaction and evaporation is 0.077 mol.

Therefore, if more than 0.077 mole of aluminum is theoretically added per mole of isopropyl alcohol, reaction heat will accumulate in the reaction system. Therefore, the upper limit of the total amount of aluminum added in the present invention is 0.17 per mole of isopropyl alcohol, taking into account heat loss, etc.
It is a mole. Furthermore, in order to effectively utilize the heat of reaction without relying on the heater 3 shown in FIG. 1, the lower limit of the total addition amount of aluminum is required to be 0.005 mol per mol of isopropyl alcohol.

Further, the aluminum to be added to isopropyl alcohol is aluminum powder 8 (FIG. 1) having a large specific surface area because it is necessary to adjust the amount added to minute units and because it is necessary to react quickly with a small amount. In order to introduce this aluminum powder 8 into the reactor 1 containing isopropyl alcohol 2,
An introduction section 7 for aluminum powder 8 is provided in the upper part of the reactor 1 .

In addition, when introducing this aluminum powder 8, in order to prevent alcohol vapor and hydrogen, which is a byproduct of aluminum and alcohol, from exploding in the reactor, the aluminum powder is surrounded with nitrogen inert gas before being introduced. It is better to do so.

[Function] If aluminum is added to isopropyl alcohol under the above conditions, isopropyl alcohol vapor will continue to be generated even if the heating amount of heater 3 shown in FIG. The reaction with the aluminum lump 5 continues to produce aluminum isopropoxide. In other words,
The purpose of heating the isopropyl alcohol 2 by the heater 3 is to smoothly cause a reaction between the alcohol and aluminum.If the total amount of aluminum added is close to the upper limit (0.17 mol of aluminum per 1 mol of alcohol) Heating can be done in a short time, or even without heating, the heat balance can be maintained and aluminum alkoxide can be synthesized without heat accumulation in the reaction system.

[Effects of the Invention] As described above, according to the present invention, a predetermined amount of aluminum powder is added to liquid alcohol as energy for generating alcohol vapor in a method for synthesizing aluminum alkoxide by bringing alcohol vapor into contact with amminium lumps. By introducing alcohol at a rate of Can be omitted, b○ Aluminum alkoxide can be generated in liquid alcohol even in the process of generating alcohol vapor, and aluminum alkoxide can be synthesized efficiently with a small device. c○ Aluminum is in the form of powder. Because of this, the response of the reaction is good, the amount added can be easily adjusted down to minute units, and the reaction heat can be easily controlled. It has excellent effects such as easy operation.

EXAMPLES Next, examples and comparative examples of the present invention will be described in detail based on the drawings, but the examples described below do not limit the technical scope of the present invention.

Example 1 As shown in FIG. 1, 800 ml of isopropyl alcohol 2 was placed in a first reactor 1 consisting of a 1000 ml round bottom flask, and a mantle heater 3 with a power consumption of 100 W was used. Further, aluminum powder 8 was continuously introduced from the introduction section 7 at a rate of 0.5 g per minute for 2 hours. The total amount of aluminum powder introduced per 800ml of alcohol is 60g,
The amount was 0.167 mol per mol of alcohol.

Further, in this example, the temperature of isopropyl alcohol 2 was raised to the boiling point of 82° C. using heater 3, and electricity was applied to heater 3 for 1 hour until isopropyl alcohol vapor was generated. After this isopropyl alcohol vapor was generated, the power to the heater 3 was turned off, and for the next two hours, isopropyl alcohol vapor was generated using the heat of formation of aluminum isopropoxide by introducing the aluminum powder 8 as a heat source.

As a result, aluminum isopropoxide was continuously synthesized in the reactor 4. As a result,
The power consumption of heater 3 was 0.1KWh. Also,
Approximately 600 g is produced by reacting 60 g of aluminum powder with isopropyl alcohol and 20 g of aluminum lump with isopropyl alcohol vapor.
of aluminum isopropoxide was synthesized.

Comparative Example A first reactor consisting of a 1000 ml round bottom flask identical to Example 1 was charged with 600 ml of isopropyl alcohol.
I put ml. Isopropyl alcohol vapor was generated by heating this isopropyl alcohol externally using a mantle heater with a power consumption of 100W. The generated isopropyl alcohol vapor is introduced into a second reactor filled with aluminum ingots, the isopropyl alcohol vapor is condensed by a Liebig condenser on the second reactor, and then passed through the second reactor to a second reactor. It was allowed to flow down into one reactor.

In this comparative example, the isopropyl alcohol in the first reactor was evaporated by continuing to heat with the heater without introducing aluminum powder, and the isopropyl alcohol vapor was led to the second reactor to form an aluminum lump. Aluminum isopropoxide was synthesized by the reaction.

In this comparative example, as in Example 1, electricity was applied to the heater for only 1 hour for preheating, and then electricity was applied for 2 hours to maintain the synthesis of aluminum isopropoxide inside the second reactor. The power consumption in this comparative example was 0.3 KWh, and about 150 g of aluminum isopropoxide was synthesized by reacting 20 g of aluminum ingot with isopropyl alcohol vapor.

Example 2 As shown in FIG.
Heated by passing steam (gauge pressure 2Kg/cm ² ) through 400% isopropyl alcohol 1
2 was preheated to a boiling point of around 82°C. Next, aluminum powder 18 was introduced into the reactor 11 at a rate of 300 g per minute for 1 hour through an aluminum introduction section 17 configured to allow continuous introduction, and aluminum isopropoxide was synthesized within the reactor 11. this alcohol
The total amount of aluminum powder introduced to 400 was 18 kg, which was 0.1 mole per mole of alcohol.

Next, the steam to the heater 13 of the external jacket is cut off, and the isopropyl alcohol vapor is guided by the heat of reaction between the isopropyl alcohol 12 and the introduced aluminum powder 18 to the second reactor 14 in which the aluminum lump 15 is housed. The isopropyl alcohol vapor in the condenser 16 was condensed, and the isopropyl alcohol was allowed to flow down into the reactor 11 through the reactor 14 and perforated plate 19. Under these conditions, the reaction between the aluminum lump 15 housed in the reactor 14 and isopropyl alcohol vapor started, and aluminum isopropoxide could be synthesized stably.

In the above example, the reaction heat generated when synthesizing aluminum isopropoxide from aluminum and isopropyl alcohol is used as a heat source, and the generated isopropyl alcohol vapor and the vapor are introduced into the second reactor. The reaction was completed by passing steam through the external jacket heater 13 for a short period of time before alcohol vapor began to be generated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus for synthesizing aluminum alkoxide according to an embodiment of the present invention. FIG. 2 is a block diagram of another embodiment of the synthesis apparatus of the present invention. 1,11: First reactor, 2,12: Isopropyl alcohol, 3,13: Heater, 4,14:
Second reactor, 5, 15: Aluminum lump, 6,
16: Capacitor, 7, 17: Introduction part of aluminum powder, 8, 18: Aluminum powder.

Claims (1)

[Claims] 1. A step of heating the isopropyl alcohol stored in the first reactor with a heater to vaporize a part of the alcohol, and a step of heating the isopropyl alcohol stored in the first reactor to vaporize a part of the alcohol, and a step provided in communication with the upper part of the first reactor In a method for synthesizing aluminum alkoxide, the method includes a step of synthesizing aluminum alkoxide by contacting an aluminum lump stored in a second reactor with isopropyl alcohol vapor generated in the vaporization step, wherein the vaporization step is performed by heating the heater. When the isopropyl alcohol starts to vaporize, reduce the heating amount of this heater or stop the heating, and add aluminum powder from the aluminum powder inlet installed at the top of the first reactor in a total amount of 1 1/2 lbs of isopropyl alcohol. A method for synthesizing aluminum alkoxide, which comprises introducing aluminum alkoxide into the first reactor at a rate of 0.005 to 0.17 moles per mole, reacting with the alcohol, and vaporizing the alcohol by the heat of reaction.