KR101718843B1 - Method for preparing of high purity aluminium oxide precursor - Google Patents

Abstract

Performing synthesis reaction under a catalyst of aluminum and alcohol; A first purification step of chelating the impurities during or after the synthesis reaction; And heating the first purified mixture to perform distillation and second refining. The present invention also provides a method for producing a precursor of high purity aluminum oxide.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a precursor of high purity aluminum oxide,

The technology disclosed in this specification relates to a method for producing a precursor of high purity aluminum oxide, which is used as a starting material for fine ceramics, electronic parts, raw materials for precision ceramics, raw materials for high purity alumina and the like and applied to advanced materials.

Alumina precursors such as aluminum alkoxide are important raw materials for obtaining a-alumina (a-Al ₂ O ₃ ) widely used in refractories, abrasives, insulators, electronic components, spark plugs, fillers, catalyst carriers and the like. Particularly, the purity of a-alumina (a-Al ₂ O ₃ ) in a fine ceramics, an electronic part, a material of a precision ceramic, and an SMR catalyst carrier is a decisive factor that determines the properties of a product, Purity is also very important.

As a conventionally known method for producing an alumina precursor, there is a method in which an alcohol is added to aluminum halide and an alkoxide is produced. According to Japanese Unexamined Patent Publication (Kokai) No. 1991-342574, which discloses such a technique, Discloses a method for producing an alkoxide by adding one or two kinds of gallium and indium at 50 ppm (in terms of metal conversion) or less. However, as a technique for producing a high purity alkoxide by using a high purity raw material of 99.99% pure aluminum But does not include refining techniques for making high purity aluminum raw materials.

Further, as a known method for producing an alumina precursor, there is a method in which an alcohol is added to metal aluminum and an initiator is added to prepare an alkoxide by the reaction. However, the materials such as Si, Fe, and Na included in the alumina precursor act as impurities in the production of high purity a-alumina. Therefore, the content of impurities such as Si, Fe, and Na in the alumina precursor should be reduced to less than 50 ppm, and the purity of the alumina precursor should be higher than 99.995%.

Therefore, there is still a need for a technique for effectively removing impurities using aluminum raw materials of lower purity and for producing aluminum alkoxide having a high purity as an alumina precursor.

It is an object of the present invention to provide a method of manufacturing a high purity aluminum oxide precursor even when low purity aluminum is used because impurities can be removed easily and efficiently.

According to one aspect of the techniques disclosed herein,

Performing synthesis reaction of aluminum and alcohol;

A first purification step of chelating the impurities during or after the synthesis reaction; And

And heating the first purified mixture at 150 ° C. or higher to perform distillation and second refining.

According to the method for producing a precursor of an aluminum oxide disclosed in the present specification, a precursor of a high purity aluminum oxide can be produced using low purity aluminum. Therefore, the aluminum oxide precursor produced according to the technique disclosed in this specification can easily produce a high purity product such as a bayer method, and the productivity can be greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram illustrating a method of making precursors of high purity aluminum oxide, an embodiment of the techniques disclosed herein.

Hereinafter, a method for producing a precursor of high purity aluminum oxide disclosed in this specification will be described in detail.

The embodiments of the present invention will now be described more fully with reference to the accompanying drawings, but it should be understood that the present invention is not limited to the specific embodiments described below. In the drawings, portions not relating to the description have been omitted so as to clearly explain the techniques disclosed in this specification.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram illustrating a method of making precursors of high purity aluminum oxide, an embodiment of the techniques disclosed herein. Referring to FIG. 1, as a step 110, a synthesis reaction of aluminum and an alcohol (for example isopropanol) is carried out.

The aluminum is not particularly limited, and for example, low purity aluminum can be produced as a precursor of high purity aluminum oxide through the technique disclosed in this specification. It may be desirable to perform surface cleaning for the purpose of removing impurity components attached to the surface of the aluminum. The surface cleaning may be performed by using water containing a surfactant, by using organic or inorganic acids, or by using alcohol used for the reaction. If necessary, two or more of them may be applied can do.

The alcohol used in the synthesis reaction is not limited thereto, but C ₂ to C ₄ alcohols can be used. Specifically, it is preferable to use at least one selected from the group consisting of ethyl alcohol, propyl alcohol, isopropyl alcohol, primary butyl alcohol, secondary butyl alcohol and tertiary butyl alcohol.

The aluminum and the alcohol can be synthesized according to the following reaction formula, for example, and the following reaction formula is not limited to the reaction formula according to one embodiment of the present invention.

Al + 3C ₃ H ₇ OH -> Al (OC ₃ H ₇ ) ₃ + 3/2 H ₂

In the synthesis reaction of aluminum and alcohol, a catalyst may be added, and the catalyst may be an aluminum-containing catalyst while acting as an initiator. Specifically, it is preferably at least one selected from the group consisting of AlCl ₃ anhydride, AlCl ₃ .6H ₂ O hexahydrate, and aluminum alkoxide. The aluminum alkoxide is preferably an aluminum alkoxide produced in the synthesis step, and when the aluminum alkoxide is used as a catalyst, an effect of reducing impurities can be provided.

It is preferable to carry out the heat treatment in the synthesis reaction. The heat treatment conditions may be at least the boiling point of the alcohol, and it is preferably within the range of 75 to 85 ° C.

As a step 120, during or after the synthesis reaction, a chelating treatment is carried out to separate the impurities. The chelating treatment is performed to chelate and separate impurities such as Si, Fe, and Na generated during the synthesis reaction, and may be performed during the synthesis reaction or at the time of completion of the synthesis reaction. However, It may be desirable to be carried out during the synthesis reaction. For reference, synthesis of aluminum oxide can be suppressed by introducing ozone before a sufficient synthesis reaction.

For example, the starting time may be at least 30 minutes after the start of synthesis, or may be at least one hour after starting synthesis. The maximum elapsed time at the time of starting may be after completion of synthesis, , It may be desirable to inject the mixture within 30 minutes before the completion of the synthesis (usually, 6-7 hours after the start of the synthesis), and further within 1 hour from the completion of the synthesis.

The chelating treatment can be performed by introducing ozone or irradiating with an electron beam, and ozone is preferably supplied during the synthesis reaction because it is easy to apply.

During the synthesis reaction, the chelate treatment is preferably carried out in a state where the alumina and the organic solvent are mixed uniformly.

The ozone can be put in the range of 300 to 900 ppm. Preferably within the range of 400 to 900 ppm, and the chelating treatment can sufficiently be carried out with respect to the impurities within this range. Additional synthetic reactions may be performed for 2 to 5 hours, or 2 to 4 hours after the ozone treatment, and the chelation treatment may be further performed if necessary during the further synthesis reaction.

The electron beam treatment can be performed under an electron beam irradiation condition of 0.7 to 3.0 MeV.

Further comprising, as step 130, heating the first purified mixture to effect distillation and a second purification step. According to the invention disclosed in the present specification, the impurities can be separated and removed in two stages. Therefore, it is preferable that the distillation is performed under a temperature condition higher than the temperature at which the impurities present in the aluminum oxide are distilled. For example, , Or once at 150 to 250 ° C, an aluminum oxide precursor of sufficiently high purity can be obtained by utilizing the vaporization characteristics of the alkoxide. It is also preferable to control the pressure since the distillation efficiency can be increased by controlling the pressure.

That is, according to the technique disclosed in the present specification, the impurities are separated in advance in the synthesis reaction step and then subjected to the one-time distillation step, so that the complexity of the process can be eliminated and a precursor of aluminum oxide of high purity can be obtained.

Wherein the aluminum oxide precursor is represented by Formula 1

[Chemical Formula 1]

Wherein R ₁ , R ₂ , and R ₃ are each independently selected from hydrogen or a substituted or unsubstituted C 1 -C 8 alkyl group, M is aluminum, and n is 3.

The precursor of the high purity aluminum oxide has a purity of 99.99% or more and may be an aluminum alkoxide such as aluminum isopropoxide, aluminum butoxide, aluminum ethoxide and the like. Preferably, aluminum isopropoxide having a purity of 99.99% or more may be used. The substitution is not limited thereto, but includes halide, alkoxy and the like.

The precursor of the high purity aluminum oxide obtained by the method disclosed herein has a purity of not less than 99.99% and not more than 5 ppm of Si, not more than 2 ppm of Fe, not more than 5 ppm of Mg and not more than 1 ppm of Cu and can be used as a precursor for providing high purity alumina .

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are provided to illustrate the present invention, but the present invention is not limited thereto.

(Example)

The aluminum used for the experiment was 5mm x 30mm and the total amount was 100g. The contents of impurities (Si, Fe, Na, Mg, Cu, Ca, Zn, Cr, Ti, Mn, K) and contents in aluminum were analyzed by ICP.

≪ Example 1 >

Aluminum is added to aluminum of purity of 99.5% prepared above, and the synthesis reaction process is carried out while maintaining 70 to 90 ° C. AlCl ₃ or aluminum isopropoxide is used as a catalyst in an amount of 0.1 mol% (equivalent ratio of Al component) Respectively.

During the synthesis reaction, ozone (O ₃ ) was added once to AlCl ₃ when the AlCl ₃ was completely mixed with the alcohol (when the color of the mixture was white uniformly), thereby chelating the impurities dissolved in the liquid phase. For reference, it was added at 1 hour after the start of synthesis. The input condition of ozone was 300 ~ 900ppm, and the content of liquid aluminum oxide was 3 ~ 7L. The synthesis reaction was carried out for 2 to 5 hours after the addition of ozone.

The obtained synthetic reaction product was heated at 150 캜 and the distillation amount was measured. As a result, it was confirmed that distillation was possible at 3.8 g / min or more. The synthetic reaction product obtained was maintained at 60 ° C or lower for 1 hour or more, and then the flocculation removal ratio of impurities was measured. As a result, it was confirmed that the removal rate of about 15% was obtained.

The purity was 99.99% and the residual impurities were found to be Si = 5 ppm, Fe = 2 ppm, Na = 10.5 ppm, Mg = 5 ppm, and Cu = 1 ppm as a result of commissioning purity measurement by Korea Basic Science Institute (KBSI).

≪ Example 2 >

The same procedure as in Example 1 was repeated except that the synthesis reaction was carried out for 6 hours in Example 1 and AlCl ₃ was added to the alcohol corresponding to the termination of the reaction, and ozone (O ₃ ) was added after 1 hour.

The result of the synthesis reaction was heated to 150 캜, and the distillation amount was measured. As a result, it was confirmed that distillation was possible at 3.1 g / min or more. The result of the synthesis reaction was maintained at 60 ° C or lower for 1 hour or longer, and the removal rate of the impurity was measured to be about 12%.

≪ Comparative Example 1 &

The synthesis reaction was carried out in the same manner as in Example 1, and a general distillation method for removing impurities was used. That is, 3 L of each distilled water was used as a solvent for removing impurities, and the temperature of the liquid was maintained at 80 ° C. It was distilled three times repeatedly to obtain a purity of 99% or more. Further, the distillation condition was 150 ° C.

The result of the synthesis reaction was maintained at 60 ° C or lower for 1 hour or longer, and then the flocculation removal ratio of impurities was measured. As a result, it was confirmed that the removal rate was about 3%.

Also, as a result of requesting purity measurement by Korea Basic Science Institute (KBSI), purity was 99.99%, and residual impurity contents were found to be Si = 50 ppm, Fe = 30 ppm, Na = 10 ppm, Mg = 10 ppm and Cu = 10 ppm.

< Comparative Example  2>

In Example 1, the same experiment was repeated except that ozone was added prior to the synthesis reaction. As a result, it was confirmed that the synthesis of aluminum oxide was lowered to 20% by weight in the result of the synthesis reaction, so that it was not possible to carry out a purification experiment to give significance level.

As a result, it was confirmed that precursors of aluminum oxide of high purity can be produced from low purity aluminum compared to Comparative Example 1 in which ozone treatment was not performed in Examples 1 and 2 in which ozone treatment was performed according to the technique disclosed in this specification In Comparative Example 2 in which ozone was introduced before the synthesis reaction, the synthesis efficiency itself was poor, and it was difficult to give significance levels to the purification process.

Claims (8)

Performing synthesis reaction under a catalyst of aluminum and alcohol;
A first purification step of chelating the inorganic impurities during or after the synthesis reaction to separate inorganic impurities; And
Heating the first purified mixture to perform distillation and second purification to provide a compound of formula 1: &lt; EMI ID =
[Chemical Formula 1]

Wherein R ₁ , R ₂ and R ₃ are independently selected from hydrogen or a substituted or unsubstituted C ₁ -C ₈ alkyl group, M is aluminum and n is 3, The method according to claim 1,
Wherein the alcohol is at least one selected from the group consisting of ethyl alcohol, propyl alcohol, isopropyl alcohol, primary butyl alcohol, secondary butyl alcohol and tertiary butyl alcohol. The method according to claim 1,
Wherein the catalyst is at least one selected from the group consisting of AlCl ₃ anhydride, AlCl ₃ .6H ₂ O hexahydrate, and aluminum alkoxide. The method according to claim 1,
Wherein the chelating treatment is carried out at 300 to 900 ppm of ozone. The method according to claim 1,
Wherein the chelating treatment is carried out after 30 minutes from the initiation of the synthesis, during the synthesis reaction. The method according to claim 1,
Wherein the distillation is carried out once at a temperature of 150 DEG C or higher. delete The method according to claim 1,
Wherein the precursor of the high purity aluminum oxide is at least 99.99% pure and at least one selected from the group consisting of aluminum isopropoxide, aluminum butoxide and aluminum ethoxide.

Images