KR20110054992A - Oxygen adsorbent having high sorption capacity for oxygen and thermal stability and preparation method thereof - Google Patents

Abstract

PURPOSE: An oxygen selective absorber and a method for preparing the same are provided to uniformly form a protective film on the surface of barium-contained compound using magnesium oxide. CONSTITUTION: Magnesium alkoxide is dissolved in alcohol in order to obtain magnesium oxide precursor solution. A barium-contained compound is dispersed in the magnesium oxide precursor solution in order to solate the dispersion solution. Distilled water is added to the solated dispersion solution in order to be gelated. The gelated dispersion solution is undergone a drying process and a sintering process.

Description

 OXYGEN ADSORBENT HAVING HIGH SORPTION CAPACITY FOR OXYGEN AND THERMAL STABILITY AND PREPARATION METHOD THEREOF}

The present invention relates to an oxygen selective adsorbent for producing high purity oxygen by selectively adsorbing oxygen from air and a method of preparing the same. More specifically, a barium-containing compound having low thermal stability is coated with magnesium oxide using a sol-gel method. The present invention relates to an oxygen selective adsorbent having high thermal stability and excellent oxygen adsorption amount and a method for producing the same.

Barium oxide is converted to barium peroxide through the oxidation reaction represented by the following Chemical Formula 1 by reacting with oxygen, and it is well known as a substance which adsorbs oxygen during this process and releases oxygen through a reduction reaction in an oxygen-free atmosphere. This characteristic of barium was used in the process of producing oxygen in the early 20th century.

[Formula 1]

However, barium peroxide does not have thermal stability at high temperatures, so it tends to lose oxygen adsorption capacity as the cycle progresses. More specifically, barium peroxide is a thermally unstable material, which may cause sintering between particles at a high temperature. As a result, the size of the particles increases and oxygen adsorption capacity is gradually lost as the process proceeds. It is possible to prepare an oxygen selective adsorbent that can maintain the adsorption capacity only by preventing such a phenomenon. In addition, barium peroxide has a high reactivity and easily reacts with other inorganic or metal components to lose the bonding property with oxygen, thereby making it possible to stably protect the barium component (barium oxide) that selectively adsorbs oxygen. It is necessary.

In order to solve this problem, various methods have been attempted. US Patent No. 3,773,680 and US Patent No. 3,903,010 disclose that barium oxide can be immobilized on dolomite to increase the utilization of barium and to increase reactivity. In the U.S. patent, the oxygen selective adsorbent was prepared by simply mixing barium oxide and dolomite solids with each other to form a pellet at high pressure.

U.S. Patent No. 4,092,264 discloses impregnating zirconia with barium oxide to produce an oxygen adsorbent with improved barium utilization and improved stability. A method of impregnating barium oxide disclosed in U.S. Patent No. 4,092,264 is as follows. First, porous zirconia is calcined at high temperature to remove impurities, the zirconia and barium peroxide are mixed with each other, and the obtained mixture is heated to impregnate barium peroxide into zirconia. According to the patent, the impregnation of barium peroxide in zirconia according to the above-described method increases the thermal stability, and can effectively store the heat generated from the oxidation reaction with oxygen during the operation of the oxygen production process and use this heat during reduction. The efficiency of the process is high, and impregnation of barium in zirconia at 20% or less is the most stable and can increase the utilization of barium.

In the above patents, a method of mixing or impregnating barium peroxide and a third substrate in a dry state was mainly used. However, when the method of mixing barium peroxide and the third substrate is used, the utilization of barium oxide is not high by forming a nonuniform protective film, and when the method of impregnating the barium peroxide with the third substrate is used. It is impossible to develop a material with high oxygen adsorption capacity because an excessive amount of the material must be used.

Alternatively, after mixing well with an aqueous solution of barium oxide and magnesium oxide (aqueous magnesium salt) in an aqueous solution, evaporation of water can be induced to form a precipitate, and barium oxide can be trapped in the skeleton of magnesium oxide through a high temperature firing process. . However, this method has a problem that barium oxide reacts with moisture to form barium hydroxide during the firing process, and the barium hydroxide has low stability and high reactivity, and thus is not easily calcined, and has low adsorption capacity of oxygen even after firing.

The present inventors have intensively studied a structure capable of stably protecting barium oxide that can solve the above-mentioned problems of the prior art, and an oxygen selective adsorbent having excellent thermal stability and oxygen adsorption capacity using the same. Thus, when magnesium oxide was formed on the surface of the barium-containing compound to produce an oxygen selective adsorbent, it was found to exhibit high thermal stability and excellent oxygen adsorption capacity, thus completing the present invention.

An object of the present invention is to provide an oxygen selective adsorbent having a high thermal stability and an excellent oxygen adsorption amount prepared by coating a barium-containing compound having poor thermal stability with magnesium oxide, and a method for preparing the same.

In order to achieve the above object, the present invention,

Solvating a dispersion prepared by dispersing a barium-containing compound in a magnesium oxide precursor solution (step 1);

Gelatinizing by adding distilled water to the dispersion liquidated in step 1 (step 2); And

It provides a method for producing an oxygen-selective adsorbent using a sol-gel method comprising the step of drying and calcining the gelled dispersion in step 2 (step 3).

Hereinafter, a method for preparing an oxygen selective adsorbent having thermal stability and oxygen adsorption capacity according to the present invention will be described in detail step by step.

First, the dispersion prepared by dispersing the barium-containing compound in the magnesium oxide precursor solution is solvated (step 1).

In the present invention, a dispersion prepared by dispersing a barium-containing compound in a magnesium oxide precursor solution is used to form a magnesium oxide on the surface of the barium-containing compound to prepare an oxygen-selective adsorbent.

In one embodiment of the present invention, a solution prepared by dissolving magnesium alkoxide in alcohol may be used as the magnesium oxide precursor solution.

The magnesium alkoxide may include magnesium methoxide, magnesium ethoxide, magnesium propoxide, magnesium butoxide, and the like, but is not limited thereto.

As a solvent for dissolving the magnesium alkoxide to prepare a magnesium oxide precursor solution, an alcohol solvent such as methanol, ethanol, propanol, butanol can be used, and methanol is preferably used.

In preparing the magnesium oxide precursor solution, the magnesium alkoxide may be included in an amount of 2 to 15 wt% based on the total weight of the magnesium oxide precursor solution.

In preparing the magnesium oxide precursor solution, it is preferable to include magnesium alkoxide in an amount of 2 to 15% by weight based on the total weight of the magnesium oxide precursor solution.

In one embodiment of the present invention, as the magnesium oxide precursor solution, a solution prepared by dissolving a magnesium salt in a citric acid solution or a mixed solution of citric acid and ethylene glycol (EG) may be used.

As the magnesium salt, magnesium nitrate (Mg (NO ₃ ) ₂ , magnesium chloride (MgCl ₂ ), magnesium acetate ((CH ₃ COO) ₂ Mg.4H ₂ O), or the like may be used, but is not limited thereto.

After the magnesium oxide precursor solution is prepared as described above, a dispersion prepared by dispersing the barium-containing compound in the magnesium oxide precursor solution is prepared and solvated.

As the barium-containing compound, barium oxide (BaO), barium hydroxide (Ba (OH) ₂ ), barium carbonate (BaCO ₃ ), barium nitrate (Ba (NO ₃ ) ₂ ), and the like may be used.

When the barium-containing compound is dispersed in the magnesium oxide precursor solution, it is preferable to use a barium-containing compound such that the magnesium / barium (Mg / Ba) molar ratio is 1 to 10.

Next, distilled water is added to the solvated dispersion and gelled (step 2).

Distilled water added to gel the dispersion liquidated in step 2 is a magnesium oxide precursor It is preferably used in an amount of 0.1 to 10 relative to mole.

When the distilled water is used less than 0.1 mole of the magnesium oxide precursor in the gelation process, the gelation process is slow or does not occur, and when the distilled water is used more than 10 moles of the magnesium oxide precursor in the gelation process, the barium component is active during the firing process. You can lose it.

As described above, when distilled water is added to the solvated dispersion prepared in Step 1, the dispersion is subjected to a solvation process, thereby forming a gel.

Finally, the gelled dispersion is dried and calcined to produce the oxygen selective adsorbent of the present invention (step 3).

The gelled dispersion in step 3 is preferably dried for 3 to 12 hours at 40 to 90 ℃ and calcined at 500 to 900 ℃.

As described above, when the oxygen-selective adsorbent of the present invention is prepared using the sol-gel method, the oxygen-selective adsorbent is prepared in an organic solvent atmosphere, thereby suppressing the formation of barium hydroxide during the firing process and collecting the barium-containing compound with a small amount of magnesium oxide. The film can be formed into a film, and the thermal stability of the oxygen selective adsorbent can be increased, and the oxygen adsorption capacity can be improved.

The present invention also provides an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity prepared by coating magnesium oxide on the surface of a barium-containing compound by using a sol-gel method.

The process of coating the magnesium oxide on the barium-containing compound surface by using the sol-gel method can be carried out in the same manner as the method for producing the oxygen selective adsorbent of the present invention described above.

The present invention provides an oxygen selective adsorbent having excellent thermal stability and oxygen adsorption capacity by forming a protective film on the surface of a barium-containing compound uniformly using a small amount of magnesium oxide by forming a magnesium oxide film on the surface of the barium-containing compound by using a sol-gel method. It may provide a method for producing the same.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

< Example >

Example  One

30 cc of magnesium methoxide solution was prepared by dispersing the methanol methoxide content in 6-10% by weight. Thereafter, barium peroxide was evenly dispersed in a 30 cc magnesium methoxide solution to prepare a dispersion, and then slowly distilled water was added to the dispersion to gelate the dispersion. The gelled dispersion was dried at 40 ° C. for 3 hours, methanol was removed at 80 ° C., and then calcined at 900 ° C. to prepare an oxygen selective adsorbent of the present invention, and an electron micrograph was taken of the prepared oxygen selective adsorbent. 1 is shown.

Example  2

An oxygen-selective adsorbent was prepared in the same manner as in Example 1 except that 20 cc of methanol was further added to the magnesium methoxide solution prepared in Example 1 to disperse barium peroxide. An electron micrograph was taken and shown in FIG. 2.

Comparative example  One

1.5 g of barium peroxide and 1.5 g of magnesium oxide were simultaneously dispersed in 50 cc of distilled water, and this dispersed aqueous solution was slowly heated to evaporate water. After the evaporation process, a precipitate was formed, and the precipitate was calcined at 900 ° C. to prepare an oxygen selective adsorbent, and an electron microscope photograph of the prepared oxygen selective adsorbent was shown in FIG. 3.

Test Example  1-electron micrograph

Electron micrographs (FIG. 1 and FIG. 2) taken for the oxygen selective adsorbents prepared in Examples 1 and 2 prepared according to the present invention and electron micrographs of the oxygen selective adsorbent prepared in Comparative Example 1 (FIG. Comparing 3), it can be observed that the oxygen selective adsorbent prepared by the sol-gel method according to the present invention is more densely covered with magnesium oxide than the oxygen selective adsorbent prepared in Comparative Example 1.

Test Example  2-Determination of oxygen adsorption capacity according to the content of barium-containing compounds

Oxygen-selective adsorbents were prepared in the same manner as in Example 1 using magnesium / barium molar ratios (Mg / Ba) of 1, 2, 4, and 5.5 molar ratios, followed by gravimetric analysis. The oxygen adsorption capacity of the oxygen selective adsorbent was measured and the results are shown in FIG. 5.

Referring to FIG. 5, it can be seen that as the molar ratio of magnesium / barium decreases, that is, as the content of the barium-containing compound increases, the oxygen adsorption capacity increases and stays at the level of 1.5 mmol / g without any further increase. Since theoretical oxygen absorption of barium oxide is 3.2 mmol / g, when the molar ratio (Mg / Ba) of magnesium / barium having a weight ratio of 1: 1 is 4, the oxygen adsorption amount should be 1.6 mmol / g, but 0.8 mmol / g. The oxygen adsorption capacity of g was shown, indicating that only 50% of barium was used for oxygen adsorption.

Test Example  3-long term of oxygen selective adsorbent Adsorption and desorption  Characteristic experiment

The weights of the oxygen selective adsorbents prepared in Example 1 and Comparative Example 1 were measured with time, and are shown in FIGS. 6 and 7, respectively. 6 shows the weight change with respect to the time of the oxygen selective adsorbent prepared in Example 1 and FIG. 7 shows the weight change with time of the oxygen selective adsorbent prepared in Comparative Example 1, the implementation of the present invention The oxygen selective adsorbent prepared in Example 1 hardly increases the weight after desorption even if the cycle progresses during regeneration, but the oxygen selective adsorbent prepared in Comparative Example 1 can be seen that the weight continues to increase as the cycle progresses during the regeneration. . From this it can be seen that the oxygen selective adsorbent prepared according to the present invention is more stable.

1 is an electron micrograph taken of the oxygen selective adsorbent prepared in Example 1 of the present invention.

2 is an electron micrograph taken of the oxygen selective adsorbent prepared in Example 2 of the present invention.

3 is an electron micrograph taken of the oxygen selective adsorbent prepared in Comparative Example 1 of the present invention.

4 is an electron micrograph taken of the barium peroxide used in Example 1 of the present invention.

Figure 5 is a graph showing the results of measuring the oxygen adsorption capacity of the oxygen selective adsorbent prepared by varying the molar ratio (Mg / Ba) of magnesium oxide / barium in Test Example 2 of the present invention.

Figure 6 is a graph showing the weight change with time of the oxygen selective adsorbent prepared in Example 1 of the present invention.

Figure 7 is a graph showing the weight change with time of the oxygen selective adsorbent prepared in Comparative Example 1.

Claims (22)

Solvating a dispersion prepared by dispersing a barium-containing compound in a magnesium oxide precursor solution (step 1); Gelatinizing by adding distilled water to the dispersion liquidated in step 1 (step 2); And Drying and calcining the gelled dispersion in step 2 (step 3) Method of producing an oxygen selective adsorbent having a high thermal stability and oxygen adsorption capacity comprising a. The method of claim 1, The magnesium oxide precursor solution is prepared by dissolving magnesium alkoxide in alcohol, the method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 2, The magnesium alkoxide is magnesium methoxide, magnesium ethoxide, magnesium propoxide or magnesium butoxide, the method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 2, The alcohol is a method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that selected from the group consisting of methanol, ethanol, propanol and butanol. The method of claim 2, The magnesium oxide precursor solution is a method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that containing 2 to 15% by weight of magnesium alkoxide relative to the total weight. The method of claim 1, The magnesium oxide precursor solution is prepared by dissolving a magnesium salt in a citric acid solution or a mixed solution of citric acid and ethylene glycol, the method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 6, The magnesium salt is magnesium nitrate (Mg (NO ₃ ) ₂ , magnesium chloride (MgCl ₂ ) or magnesium acetate ((CH ₃ COO) ₂ Mg.4H ₂ O) characterized in that the oxygen having high thermal stability and oxygen adsorption capacity Method for preparing a selective adsorbent. The method of claim 1, The barium-containing compound is selected from the group consisting of barium oxide (BaO), barium hydroxide (Ba (OH) ₂ ), barium carbonate (BaCO ₃ ) and barium nitrate (Ba (NO ₃ ) ₂ ) A method for producing an oxygen selective adsorbent having thermal stability and oxygen adsorption capacity. The method of claim 1, The method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, wherein the barium-containing compound dispersed in the magnesium oxide precursor solution in step 1 is used such that the molar ratio of magnesium / barium is 1 to 10. The method of claim 1, Distilled water added for the gelation in step 2 is a method of producing an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that added to the dispersion in an amount of 0.1 to 10 relative to the molar magnesium oxide precursor. The method of claim 1, The gelled dispersion in step 3 is dried for 3 to 12 hours at 40 ~ 90 ℃ and calcined at 500 ~ 900 ℃ characterized in that the high thermal stability and oxygen adsorption capacity of the oxygen selective adsorbent manufacturing method. An oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity prepared by coating magnesium oxide on the surface of a barium-containing compound by using a sol-gel method. The method of claim 12, The step of coating the magnesium oxide on the barium-containing compound surface by using the sol-gel method comprises the steps of: solvating the dispersion prepared by dispersing the barium-containing compound in the magnesium oxide precursor solution; Gelling the distilled water by adding distilled water to the solvated dispersion; And drying and calcining the gelled dispersion, an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 13, The magnesium oxide precursor solution is an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that prepared by dissolving magnesium alkoxide in alcohol. The method of claim 14, The magnesium alkoxide is magnesium methoxide, magnesium ethoxide, magnesium propoxide or magnesium butoxide, the oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 14, The alcohol is an oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that selected from the group consisting of methanol, ethanol, propanol and butanol. The method of claim 14, The magnesium oxide precursor solution is oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that containing 2 to 15% by weight of magnesium alkoxide relative to the total weight. The method of claim 13, The magnesium oxide precursor solution is prepared by dissolving a magnesium salt in a citric acid solution or a mixed solution of citric acid and ethylene glycol, oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity. The method of claim 18, The magnesium salt is magnesium nitrate (Mg (NO ₃ ) ₂ , magnesium chloride (MgCl ₂ ) or magnesium acetate ((CH ₃ COO) ₂ Mg.4H ₂ O) characterized in that the oxygen having high thermal stability and oxygen adsorption capacity Selective adsorbent. The method of claim 13, The barium-containing compound is selected from the group consisting of barium oxide (BaO), barium hydroxide (Ba (OH) ₂ ), barium carbonate (BaCO ₃ ) and barium nitrate (Ba (NO ₃ ) ₂ ) Oxygen selective adsorbent with thermal stability and oxygen adsorption capacity. The method of claim 13, Distilled water added for the gelation is oxygen selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that added to the dispersion in an amount of 0.1 to 10 relative to the molar magnesium oxide precursor. The method of claim 13, Oxygen-selective adsorbent having high thermal stability and oxygen adsorption capacity, characterized in that the molar ratio of magnesium / barium in the oxygen-selective adsorbent is 1 to 10.

Images