WO2012100556A1

WO2012100556A1 - Process for the preparation and solidification of lower aluminum alkoxide

Info

Publication number: WO2012100556A1
Application number: PCT/CN2011/080381
Authority: WO
Inventors: Jiasong LIAN; Zhongbang ZHU; Xiaoxia Li
Original assignee: Lianyungang Lianlian Chemicals Co., Ltd.
Priority date: 2011-01-26
Filing date: 2011-09-29
Publication date: 2012-08-02
Also published as: CN102153447B; CN102153447A

Abstract

It is provided in the invention a process for the preparation of a fast solidifying aluminum isopropoxide of high purity, comprising providing lower aluminum alkoxide, and adding solid lower aluminum alkoxide as a solidifying agent into the liquid aluminum to yield the solidified lower aluminum alkoxide. Specificially, when the temperature of the liquid lower aluminum alkoxide is lowered to 40-85℃, the solid lower aluminum alkoxide is added with agitation as the solidifying agent. Generally, the solid lower aluminum alkoxide is added in an amount of 0.5-20% by weight, based on the liquid lower aluminum alkoxide. Then the solution is placed at a temperature of 20-85℃, and it will completely solidify within 24 hours. The lower aluminum alkoxide prepared via the present process has a high purity and can completely solidify within 24 hours, which is one seventh to one fifth of the conventional solidification time. The process is highly efficient and clean, and it will reduce the solidification time without reducing the purity and quality of the lower aluminum alkoxide.

Description

PROCESS FOR THE PREPARATION AND SOLIDIFICATION OF

LOWER ALUMINUM ALKOXIDE

TECHNICAL FIELD

The invention relates to a process for the preparation and solidification of lower aluminum alkoxide, especially a process for the preparation and solidification of lower aluminum alkoxide having a high purity.

BACKGROUND

Lower aluminum alkoxide can be widely used in fields such as catalyst, dehydrating agents and pharmaceutical intermediates, and it is also an important precursor for palletizing powders of noval ceramics and functional nanomaterials. Alkoxide salts of aluminum are prepared primarily by directly reacting metal aluminum and an alcohol followed by distillation and purification. Freshly prepared lower aluminum alkoxide is present in a liquid state and slowly solidifies after standing at room temperature for several days. The conversion from the liquid trimer to the solid tetramer is a spontaneous and slow process under the room tempture. The process takes 3-7 days.

Currently, the manufacturers that produce lower aluminum alkoxide mainly employ the method of spontaneous solidification. The disadvantages of this kind of producing lower aluminum alkoxide and letting it self solidify are that on one hand the solidification time is too long and huge room of factory building is required to harbor the unsolidified lower aluminum alkoxide; on the other hand, the too long solidification time makes it hard to increase daily output. Although a few manufacturer solidify the liquid lower aluminum alkoxide at higher or lower temperature, but the general effect is unsatisfied. Moreover, the lower aluminum alkoxide in a solid state has a higher safety and is easier to transport.

SUMMARY The invention provides a process for the preparation and solidification of lower aluminum alkoxide of high purity, which solves the problems that the preparation of lower aluminum alkoxide is time consuming and complicated, and its solidification time is too long which causes low availability of factory building space and a long period from production to packaging of the product.

To solve the above problems, the following technical solution is employed in the invention: providing the liquid lower aluminum alkoxide, and solid lower aluminum alkoxide used as a solidifying agent is added with agitation into the liquid lower aluminum alkoxide for solidification, thereby a rapid solidification is possible, and solid lower aluminum alkoxide can be obtained within 24 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the, illustrate embodiments of the invention together with the description which serves to explain the principle of the invention. Therefore, the invention is not limited to the embodiments. In the drawings:

Figure 1 : the infrared spectrum of aluminum n-butoxide.

DETAILED DESCRIPTION

An embodiment of the present invention will now be described in detail in conjunction with the drawings. In the following description, some detailed descriptions of known functions and configurations may be omitted for clarity and conciseness.

In the invention, the inventor has surprisingly found that liquid lower aluminum alkoxide can be rapidly solidified by first providing liquid lower aluminum alkoxide, then adding solid lower aluminum alkoxide as a solidifying agent into the liquid lower aluminum alkoxide with agitation for solidification, wherein the liquid lower aluminum alkoxide can be freshly prepared liquid lower aluminum alkoxide, or liquid lower aluminum alkoxide allowed for standing for a period, and it also can be liquid lower aluminum alkoxide obtained from re- melting of solid lower aluminum alkoxide.

The lower aluminum alkoxide can be prepared with the following processes: Direct Reaction: It is usually conducted in a solvent or in a solution state, comprising using metal aluminum and lower alkyl alcohol as raw materials, and generating lower aluminum alkoxide by heating for several hours in the presence of a catalyst, wherein the alcohol needs to be excessive. Subsequently, the final product lower aluminum alkoxide is obtained after subjecting to a(n) atmospheric or vacuum distillation.

Alcohol Displacement Method: For example, aluminum ethoxide and lower alkyl alcohol are used as raw materials which are heated in a liquid condition to reflux for several hours, and the lower aluminum alkoxide is prepared by displacing the ethanol in the aluminum ethoxide with the lower alkyl alcohol. Subsequently a vacuum distillation is employed and the reaction is terminated at the second boiling point to yield the lower aluminum alkoxide.

Method of Preparing Lower Aluminum Alkoxide by Gas-Solid Phase Reaction: It comprises reacting gaseous lower alkyl alcohol with metal aluminum, for example, at a temperature of refluxing the lower alkyl alcohol, to prepare the lower aluminum alkoxide.

After obtaining the lower aluminum alkoxide, preferably the lower aluminum alkoxide of high purity, this lower aluminum alkoxide of high purity is adjusted to a proper temperature, for example, 40-85 ^°C , the solidifying agent lower aluminum alkoxide, preferably lower aluminum alkoxide particle or powder is added.

In the process for the preparation of lower aluminum alkoxide, the lower alkyl alcohol may be C2-C4 saturated or unsaturated alcohol, preferably C2-C4 saturated alcohol, including ethanol, propanol, butanol, preferably iso-propanol, n-butanol, iso-butanol and tert-butanol. In the process for the preparation of lower aluminum alkoxide by gas-solid phase reaction, the lower alkyl alcohol in a gaseous state is contacted with preferably stoichiometrically excessive metal aluminum, and reacted. In the direct reaction and alcohol displacement method, the alcohol is excessive in stoichiometry, preferably excessive in molar stoichiometry.

The metal aluminum used in the process of preparation in the invention can be metal aluminum in any form, comprising, but not limited to, forms such as aluminum flake, aluminum block, aluminum particle, aluminum slag, etc. Preferably, the purity of aluminum is 99% or more. In the process for the preparation of lower aluminum alkoxide by gas-solid phase reaction, preferably the aluminum is excessive in stoichiometry. Usually, lower alkyl alcohol : aluminum is≥1 : 1 (molar ratio), preferably lower alkyl alcohol : aluminum is 1 : 3 (molar ratio), generally between 1 : 3 and 1 : 1.

When preparing the lower aluminum alkoxide by gas-solid phase method, it is required that the metal aluminum is contacted and reacted with gaseous lower alkyl alcohol rather than liquid lower alkyl alcohol, preferably the raw material metal aluminum is physically separated from the liquid lower alkyl alcohol, for example, the metal aluminum is separated from the liquid lower alkyl alcohol by using the porous material carrier. Preferably, the metal aluminum material is maintained above the lower alkyl alcohol and separated therefrom. When the liquid lower alkyl alcohol is refluxed, the gaseous lower alkyl alcohol contacts and reacts with the metal aluminum. There is no particular limitation to the separation distance between the metal aluminum and the liquid lower alkyl alcohol, as long as the surface of the lower alkyl alcohol under refluxing does not directly contact with the metal aluminum. The porous material carrier can be any material that is inert under reaction conditions, for example, comprising, but not limited to, materials such as glass, steel and nylon mesh, etc.

To facilitate the reaction, the addition of a catalyst is preferable. The catalyst includes the catalysts commonly used in the production of lower aluminum alkoxide, preferably catalysts in solid state, such as anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride catalyst. During the reaction, the catalyst can be added into the lower alkyl alcohol, or can also be placed above the porous material together with the metal aluminum raw material. In the process for the preparation of lower aluminum alkoxide by gas-solid phase reaction, it is preferable that the catalyst is in a solid state and contacts with the gaseous lower alkyl alcohol together with the metal aluminum, so as to faciliatate the reaction.

According to one aspect of the invention, it is provided a process for the preparation of lower aluminum alkoxide of high purity by a gas-solid phase reaction with metal aluminum and lower alkyl alcohol used as the raw materials, wherein the aluminum can be aluminum flake, aluminum block, aluminum turning or aluminum slag with a purity of 99% or more, and the aluminum has to be excessive, i.e., aluminum : lower alkyl alcohol > 1 : 3 (molar ratio), generally between 1 /3 and 1 , and the process is green, safe, highly efficient and has low energy consumption. The lower alkyl alcohol involved in the reaction is in a gaseous state rather a liquid state. Anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride is used as the catalyst, and 0.5 to 3.5 g of the catalyst per liter of the lower alkyl alcohol is needed.

According to one aspect of the invention, the specific process for the preparation of lower aluminum alkoxide of high purity by gas-solid phase reaction is as follows: for example, a lower alkyl alcohol such as n-butanol is added into the reactor, and then a porous mesh containing a mixture of metal aluminum and a catalyst is placed above the liquid which is then heated to reflux. When the boiling point of n-butanol (for example, 1 17.73^°C under atmospheric pressure) is reached, the evaporated gaseous n-butanol will react with the metal aluminum in the presence of the catalyst as it passes through the porous mesh, and the lower aluminum alkoxide generated will drop back into the reactor through the porous mesh. With the increase of the amount of the lower aluminum alkoxide in the reactor, the azeotropic temperature also increases. When the temperature of the liquid in the reactor reaches the boiling point of the lower aluminum alkoxide (242^°C under atmospheric pressure), all n-butanol has been exhausted by the reaction. Heating is continued for e.g. half an hour, generally 0.5-5 hours before being stopped. During the reaction, a small amount of aluminum turnings will drop. After removal of the porous mesh, the solution yielded is filtered to remove the aluminum turnings to yield the final product lower aluminum alkoxide with an impurity content of less than 0.01 %.

According to another aspect of the invention, when preparing lower aluminum alkoxide, e.g., aluminum isopropoxide, the catalyst is anhydrous aluminum trichloride, cupric chloride or stannic tetrachloride. The specific process is as follows: the isopropanol involved in the reaction is divided into 10 aliquots. Two aliquots of isopropanol and the metal aluminum are added in a certain ratio {e.g., 2-6 parts of the metal aluminum, weight ratio) into the reactor, so that the isopropanol can immerse the metal aluminum. The catalyst is added into the remaining 8 aliquots of isopropanol and mixed thoroughly, and added dropwise into the reactor within 1 -10 hours. After the completion of the reaction, the excessive alcohol is evaporated away by distillation. The remaining is the final product liquid lower aluminum alkoxide.

After the liquid lower aluminum alkoxide is prepared, the temperature of the liquid lower aluminum alkoxide, e.g., aluminum isopropoxide, is adjusted to 40- 85^°C , and solid lower aluminum alkoxide is added with agitation. After the solid lower aluminum alkoxide is evenly distributed into the liquid dlower aluminum alkoxide, the solution becomes a suspension. Optionally, agitation can be continued for a period of about 5 minutes. The amount of solid lower aluminum alkoxide added is generally 0.5-20% by weight of the liquid lower aluminum alkoxide. Alternatively, when the solid lower aluminum alkoxide is added into the liquid lower aluminum alkoxide, the solid to liquid ratio is more than 1 % by weight, preferably 1 %-20% by weight, based on the total weight of the solid and liquid lower aluminum alkoxide. Then the solution is placed at a temperature of 20-85 ^°C , and it can completely solidify within 24 hours. The lower aluminum alkoxide added as a solidifying agent is particle or pulverous solid lower aluminum alkoxide, preferably having an average particle size of less than 50 μηη, more preverably less than 20 μηη, or preferably 10-50 μηη. The inventor has surprisingly found that by adding the solid lower sluminum alkoxide as a solidifying agent with agitation, the liquid lower aluminum alkoxide can be rapidly solidified and the solidification can be completed within 24 hours, which is different from the solidification by allowing it to stand at room temperature which requires 3-7 days to convert the liquid trimer into the solid tetramer.

The major advantages of the solidification process of the invention is that, in contrast to the prior art, the liquid lower aluminum alkoxide product can be directly transported and used; the lower aluminum alkoxide prepared by the present process can completely solidify within 24 hours, which is one seventh - one fifth of the conventional solidification time; it has been surprisingly found that the process is highly efficient and clean, and shortens the solidification time, and in the meantime does not reduce the purity and quality of the lower aluminum alkoxide, and also makes the lower aluminum alkoxide easier to transport and store. Morever, by rapid solidifaction, the cycle from production to packaging of the lower aluminum is shortened, so as to increase the efficiency of factory building use, reduce the total production cost; in addition, the process does not introduce any other substances into the product, and is also green and friendly to the environment.

In particular, the process, wherein the lower aluminum alkoxide is prepared by reacting gaseous alkyl alcohol with solid metal aluminum, provides the following advantages: the raw materials is easy to obtain; the process itself is safe and convenient with a simple post processing, and requires low energy consumption, reduces the intervention of other substances during the reaction, and is able to produce lower aluminum alkoxide of high purity in a way that saves energy and is economically advantageous. Examples

Example 1 :

200 ml of isopropanol was taken and divided into 10 aliquots. 27 g of metal aluminum and 2 aliquots of isopropanol were added into the reactor and heated to reflux. 0.2 g of anhydrous aluminum trichloride used as a catalystwas weighed and added into the remaining 8 aliquots of isopropanol, mixed thoroughly, and added dropwise into the reactor within 1 -10 hrs. After the completion of the reaction, the excessive alcohol was evaporated away by distillation. The solid impurities were filtered to yield the final product liquid aluminum isopropoxide.

When the temperature of the liquid aluminum isopropoxide was lowered to 50^°C, 2g of solid aluminum isopropoxide particles or powders with an average particle size of 48 μηη is added with agitation to yield a solution with a solid to liquid ratio of 1 %. Agitation was continued for 5 minutes followed by placing the resultant solution at 70^°C. Completely solidified final product aluminum isoproxide was obtained after 18 hours.

Example 2:

500 ml of isopropanol was taken and divided into 10 aliquots. 54 g of metal aluminum and 2 aliquots of isopropanol were added into the reactor and heated to reflux. 0.6 g of cupric chloride used as a catalyst was weighed and added into the remaining 8 aliquots of isopropanol, mixed thoroughly, and added dropwise into the reactor within 1 -10 hrs. After the completion of the reaction, the excessive alcohol was evaporated away by distillation. The solid impurities were filtered to yield the final product liquid aluminum isopropoxide.

When the temperature of the liquid aluminum isopropoxide was lowered to 50^°C, 8.2 g of solid aluminum isopropoxide with an average particle size of 20 μηη is added with agitation to yield a solution with a solid to liquid ratio of 2%. Agitation was continued for 5 minutes followed by placing the resultant solution at 70^°C . Completely solidified final product aluminum isoproxide was obtained after 15 hours.

Example 3:

200 ml of isopropanol was taken and divided into 10 aliquots. 27 g of metal aluminum and 2 aliquots of isopropanol were added into the reactor and heated to reflux. 0.2 g of stannic tetrachloride used as a catalyst was weighed and added into the remaining 8 aliquots of isopropanol, mixed thoroughly, and added dropwise into the reactor within 1 -10 hrs. After the completion of the reaction, the excessive alcohol was evaporated away by distillation. The solid impurities were filtered to yield the final product liquid aluminum isopropoxide.

When the temperature of the liquid aluminum isopropoxide was lowered to 50^°C , 4 g of solid aluminum isopropoxide with an average particle size of 18 μηη is added with agitation to yield a solution with a solid to liquid ratio of 2%. Agitation was continued for 5 minutes followed by placing the resultant solution at 75^°C . Completely solidified final product aluminum isoproxide was obtained after 13.5 hours.

Example 4:

1200 ml of isopropanol was taken and divided into 10 aliquots. 162 g of metal aluminum and 2 aliquots of isopropanol were added into the reactor and heated to reflux. 2 g of anhydrous aluminum trichloride used as a catalyst was weighed and added into the remaining 8 aliquots of isopropanol, mixed thoroughly, and added dropwise into the reactor within 1 -10 hrs. After the completion of the reaction, the excessive alcohol was evaporated away by distillation. The solid impurities were filtered to yield the final product liquid aluminum isopropoxide. When the temperature of the liquid aluminum isopropoxide was lowered to 50^°C , 36.7 g of solid aluminum isopropoxide with an average particle size of 10 μηη is added with agitation to yield a solution with a solid to liquid ratio of 3%. Agitation was continued for 5 minutes followed by placing the resultant solution at 80^°C . Completely solidified final product aluminum isoproxide was obtained after 1 1 hours. Example 5:

300 ml of n-butanol was initially added into the reactor, then a porous mesh containing a mixture of aluminum and anhydrous aluminum trichloride was suspended above the liquid, wherein the aluminum turnings were 27 g and the catalyst was 0.3 g. The reaction was conducted by heating to reflux until the liquid temperature reached the boiling point of the lower aluminum alkoxide, and the heating was continued for half an hour before being stopped. After the porous mesh was removed, the resultant solution was filtered to yield the aluminum n-butoxide. The infrared assay (see Figure 1 ) shows it was aluminum n-butoxide with an impurity content of less than 0.01 %. Solidification was conducted in a similar way as above.

Comparative Example 1

Liquid aluminum isopropoxide was prepared according to the process as described in Example 1 , except that it was performed at room temperature and a solidifying agent, i.e., solid aluminum isopropoxide, was added. It took 1 18 hours to obtain the solid aluminum isopropoxide.

A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, elements of different implementations may be combined, supplemented, modified, or removed to produce other implementations. Additionally, one of ordinary skill will understand that other structures and processes may be substituted for those disclosed and the resulting implementations will perform at least substantially the same function(s), in at least substantially the same way(s), to achieve at least substantially the same result(s) as the implementations disclosed. Accordingly, these and other implementations shall fall in the scope of the invention.

Claims

1. A process for the preparation and solidification of lower aluminum alkoxide, comprising the steps of:

providing liquid lower aluminum alkoxide; and

adding solid lower aluminum alkoxide as a solidifying agent into the liquid aluminum alkoxide.

2. The process according to claim 1 , wherein the liquid lower aluminum is selected from a group consisting of: freshly prepared liquid lower aluminum alkoxide, liquid lower aluminum alkoxide after standing for a period, liquid lower aluminum alkoxide obtained from re-melting of solid lower aluminum alkoxide.

3. The process according to claim 2, wherein the liquid lower aluminum alkoxide is prepared from the reaction between gaseous lower alkyl alcohol and solid metal aluminum.

4. The process according to claim 3, wherein the reaction between the gaseous lower alkyl alcohol and the solid metal aluminum is carried out at a temperature of refluxing lower alkyl alcohol.

5. The process according to claim 4, wherein the lower alkyl alcohol is selected from the group consisting of ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol and tert-butanol.

6. The process according to claim 5, wherein the metal aluminum is selected from the group consisting of aluminum flake, aluminum block, aluminum particle and aluminum slag, preferably the metal aluminum has a purity of higher than 99% by weight.

7. The process according to any one of claims 1 to 6, wherein the solid lower aluminum alkoxide as the solidifying agent is added with agitation when the liquid lower aluminum alkoxide is maintained at 40-85^°C .

8. The process according to claim 7, wherein the solid lower aluminum alkoxide as the solidifying agent has an average particle size of less than 50 μηη.

9. The process according to claim 8, wherein the solid lower aluminum alkoxide is added in an amount of 0.5-20% by weight, based on the liquid lower aluminum alkoxide.

10. The process according to claim 9, wherein the liquid lower aluminum alkoxide, to which the solid lower aluminum alkoxide is added, is solidified at temperature of 0-85 ^°C, preferably 20-85°C .