KR100636424B1 - The preparation method of an adsorbent and the purification method of gases using the same - Google Patents

Abstract

The present invention relates to a method for preparing an adsorbent and a method for purifying a gas using the same. Specifically, when a metal precursor is supported on an inorganic carrier, the polyhydroxy alcohol and the chelating agent are added and then heated, dried, calcined and reduced. The present invention relates to a method for preparing an adsorbent in which metal ions are converted into a metal state and a method for purifying a gas using the same.

The method for preparing the adsorbent according to the present invention can be efficiently used to purify impurities, such as oxygen, carbon dioxide, and water, contained in an inert gas with high purity at a time by reducing the metal particle size and improving the dispersibility of the metal.

Description

The preparation method of an adsorbent and the purification method of gases using the same}

The present invention relates to a method for preparing an adsorbent and a method for purifying an inert gas using the same.

Inert gases such as nitrogen and helium, which are used in semiconductor processes, are very important in purity, and when the purity is low, the defect rate is significantly increased, resulting in a very low productivity. For example, when the concentration of impurities such as carbon monoxide and hydrogen in nitrogen is 5 ppb or more, the defect rate of the silicon substrate manufacturing process is greatly increased (US Pat. No. 6,572,681 and Korean Patent No. 10-300918). Therefore, in addition to inert gas such as nitrogen, air, hydrogen, carbon dioxide, hydrogen-containing gas (H ₂ , NH ₃ , PH ₃ , AsH ₃ , B ₂ H ₂ , SiH ₄ , HCl, HBr, etc.) and gases such as chlorine and bromine must be purified to very high purity in order to be used in semiconductor processes, and in many cases are removed by adsorption.

U.S. Patent No. 6,572,681 describes a method for purifying nitrogen by adsorbing and removing carbon monoxide and hydrogen using zeolites in which Mn, Fe, Ni, Cu, Ag, Pd, Co, Pt, Au are ion exchanged. Patent 6,088,301 describes a method of increasing the purity of argon or helium by adsorbing nitrogen, oxygen, carbon dioxide, carbon monoxide, as well as hydrocarbons using X-type zeolite with low silica content. Korean Patent No. 10-300918 discloses a method of oxidizing carbon monoxide to carbon dioxide for purification of nitrogen or oxygen, and oxidizing hydrogen to water using a supported platinum or palladium catalyst and then removing it using an adsorbent. It is. However, Na-X (or Ca-X) zeolites are used to remove carbon dioxide, and silica gel, activated alumina or zeolites are used to remove moisture. U. S. Patent No. 6,408, 849 describes a process for adsorption of carbon dioxide and oxygen and removal of nitrogen using a getter from inert gases such as helium and xenon.

Many techniques for purifying air are known, and various kinds of adsorbents may be used depending on the impurities to be removed. For example, US Pat. No. 6,358,302 describes the use of zeolites or alumina for the removal of NO _X , hydrocarbons, and the like, while US Pat. Nos. 6,238,460 and 6,106,593 remove carbon dioxide, water, NO _X and ethylene. The use of alumina and zeolites is described. In addition, US Pat. No. 6,074,621 describes carbon monoxide and hydrogen being oxidized using a palladium or platinum catalyst supported on alumina to be converted to carbon dioxide and water, respectively, and then adsorbed and removed. U.S. Patent No. 6,391,090 discloses water, alcohol, NO _X , SO _X , halogen, amine, hydrocarbon, CO _X , siloxane, etc. using low electronegativity metal, high silica content zeolite and post-transition metal components. It is described about a method of adsorbing to obtain compressed air of high purity, helium, nitrogen, helium / oxygen and the like. US Pat. Nos. 6,464,756, 6,261,528 and 5,558,844 describe that hydrogen gas can be purified using X-type zeolites such as LiCaX, metal hydrides, nickel and zirconium metals with low silica content. US Pat. No. 6,511,528 describes the use of zeolites, metal oxides, silica, activated carbon, and the like for the removal of compounds containing carbon, sulfur and nitrogen atoms for the purification of carbon dioxide. US Pat. No. 6,361,696 describes hydrocarbons. In order to remove, a method using a zeolite such as Y, ZSM-5, mordenite having a high silica content is described. U.S. Patent No. 6,099,619 describes a method for obtaining high purity carbon dioxide by removing sulfur, oxygen and organics using AgX or MFI zeolite. U. S. Patent No. 6,059, 859 describes a method for producing high purity carbon dioxide from which moisture is removed using titania, zirconia, yttria, vanadia and the like.

A method for purifying hydrides such as hydrogen chloride and hydrogen bromide using adsorption is also known. US Pat. No. 6,461,411 describes a method for removing SiH ₄ , H ₂ S, GeH _4, etc. using alumina. US Pat. Nos. 6,395,070 and 6,110,258 dehydrate and superheat zeolites with high silica content. The method for removing trace amounts of water is described. US Pat. Nos. 6,241,955 and 6,221,132 describe methods for purifying hydrides such as hydrogen chloride and hydrogen bromide using adsorbents such as metal oxides such as MnO _X , MoO _X or MgX ₂ supported on activated carbon. U. S. Patent No. 5,910, 292 discloses a method of increasing purity by adsorbing and removing moisture using a zeolite having a high silica content, such as chlorine and bromine.

However, in the above-mentioned method for purifying inert gas such as nitrogen and helium, the process is complicated by using various kinds of adsorbents or catalysts, or further pretreatment such as high temperature treatment of the adsorbent is required, and the metal supported on activated carbon or the like Hydrates and the like have many problems since there is always a possibility of ignition.

Therefore, in purifying an inert gas, various kinds of impurities can be removed with one adsorbent, and there is a need for developing a stable and relatively inexpensive adsorbent.

Accordingly, the present inventors add a polyhydroxy alcohol and a chelating agent when the metal precursor is supported on an inorganic carrier to solve the above problems, and then heated, dried, calcined and reduced to convert the metal ions into a metal state By adsorbing the adsorbent thus prepared to reduce the metal particle size and improve the dispersibility of the metal, it was confirmed that it is effective in purifying impurities, such as oxygen, carbon dioxide and moisture contained in the inert gas with high purity and the present invention Completed.

The present invention is to provide a method for producing an adsorbent which improves the adsorption efficiency by increasing the degree of dispersion of the supported metal and reducing the particle size.

In addition, the present invention is to provide a method for purifying a gas using the adsorbent prepared by the above production method.

The present invention provides a method for preparing the adsorbent.

The present invention also provides a method for purifying a gas using an adsorbent prepared by the above method.

Hereinafter, the present invention will be described in detail.

The preparation method of the adsorbent of the present invention

1) adding polyhydroxy alcohol and a chelating agent when heating the metal precursor on the inorganic carrier (first step),

2) drying and baking the supported metal precursor (second step), and

3) converting the supported metal precursor to a metal (third step).

Hereinafter, the method of preparing the adsorbent of the present invention will be described in detail.

In the first step, the metal component may be any metal having adsorption properties of oxygen, carbon dioxide, and water, and palladium, platinum, silver, nickel, zirconium, and the like may be used, and nickel is particularly preferable in terms of manufacturing cost. Do.

The metal precursor may be any, but a metal salt is preferable because of the simplicity and convenience of the manufacturing process, and the metal salt includes nitrate, chloride, sulfate, carbonate, hydroxide, and the like.

The carrier may be any material as long as it can withstand high temperatures in the calcination and reduction steps and has a wide surface area to increase metal dispersibility. Inorganic materials such as carbon and zeolites such as silica, alumina, silica alumina and activated carbon may be used. Carriers are preferred. In the present invention, silica having a large surface area and low cost is particularly preferable.

Precipitation or impregnation is preferable as a method of supporting the metal precursor on the inorganic carrier, and in the present invention, a simple and convenient impregnation method is particularly preferable.

In the present invention, in order to increase the dispersibility of the metal component and to reduce the particle size, polyhydroxy alcohol and a chelating agent are added and then heated when the metal precursor is supported on the inorganic carrier. The polyhydroxy alcohol is preferably ethylene glycol or propylene glycol, and the chelating agent is preferably citric acid or oxalic acid. In particular, ethylene glycol as polyhydroxy alcohol and citric acid as chelating agent are more preferable because these materials are not only convenient but also economically inexpensive. A polymer is obtained between the polyhydroxy alcohol and the chelating agent by heating, and any method of forming such a polymer may be performed at a high temperature. However, the polymer may be equilibrated by evaporating water in a vacuum using a rotary evaporator at a high temperature. It is efficient to move toward to promote polymerisation. The heating temperature is preferably 25 to 100 ° C., if the temperature is 25 ° C. or less, excessive time is required for the process, and if the temperature is 100 ° C. or more, the carrier and the metal precursor other than the material to be evaporated are not easily maintained and are easily lost.

In the second step, a method of drying a supported metal precursor, a carrier, a polymerized polyhydroxy alcohol and a chelating agent includes heating, vacuum drying, microwave drying, and the like. Drying with microwaves is preferred.

The organic material used in the preparation of the adsorbent can be removed by high temperature firing, any firing method can be used and can be decomposed by heating at 300 ~ 1000 ° C. using an electric furnace or a microwave firing furnace. If the temperature is 300 ° C or less, the baking takes a long time and is not practical, and if it is 1000 ° C or more, aggregation between particles may occur. The kiln may be fired while maintaining in an air or oxygen atmosphere to completely remove organic matters, and may be maintained in an inert gas atmosphere such as nitrogen and helium to convert organic matter to carbon to act as a carrier and an adsorbent.

In the third step, any reducing method may be applied to reduce the supported metal oxide to metal, and a reducing agent such as NaBH ₄ , KBH ₄ , formaldehyde, or hydrazine may be used, but at high temperature using hydrogen. Reducing is most simple and preferred. At this time, the reduction temperature is preferably in the range of 0 ~ 600 ℃, if the temperature is 0 ℃ or less, the reduction reaction is too slow to be practical, if the temperature is 600 ℃ or more may occur agglomeration between the metal particles.

The method for purifying the impurities present in the inert gas using the prepared adsorbent can be applied to any method, and after filling the granules filled with the adsorbent into granules to withstand pressure, passing the inert gas to remove the impurities. . Adsorption temperature and pressure may be any condition, but operating temperature at room temperature is advantageous in terms of cost, and the pressure can be changed depending on the process conditions.

The metal particle size of the adsorbent according to the present invention is 20-30 nm, which is markedly smaller than the metal particle size (51 nm) of the adsorbent without ethylene glycol and citric acid.

In addition, the adsorption amount of the adsorbent according to the present invention is represented by oxygen 3.8 ~ 4.3 cc / g, carbon dioxide 3.6 ~ 4.7 cc / g, water vapor 56 ~ 102 cc / g, the adsorption amount of the adsorbent without using ethylene glycol and citric acid Since 2.7 cc / g of oxygen, 3.0 cc / g of carbon dioxide, and 66 cc / g of water vapor appear, it can be seen that the adsorption amount of the adsorbent according to the present invention is greatly improved.

Therefore, the adsorbent according to the present invention can be effectively used to purify impurities with high purity, such as oxygen, carbon dioxide, and moisture contained in the inert gas by reducing the metal particle size and improving the dispersibility of the metal.

Hereinafter, preferred examples and experimental examples are presented to help understand the present invention. However, the following Examples and Experimental Examples are provided only to more easily understand the present invention, and the contents of the present invention are not limited by the Examples and Experimental Examples.

Example 1  : Preparation of Adsorbent

19.83 g of nickel nitrate hexahydrate (Ni (NO ₃ ) ₂ · 6H ₂ 0) was dissolved in 50 cc of distilled water, and then slowly added 2 g of silica (fumed silica) and mixed well for 1 hour. 10 g of ethylene glycol and 10 g of citric acid were continuously added thereto, followed by further stirring at room temperature for 1 hour, and then water was evaporated until it became sticky at 60 ° C. using a rotary evaporator. Thereafter, the mixture was further dried for 2 minutes using a microwave oven to obtain a hard state. Subsequently, air was flowed using an electric furnace and maintained at 600 ° C. for 3 hours to remove organics and to obtain an adsorbent precursor in which nickel oxide was supported on silica.

After the granules were granulated by applying pressure to the adsorbent precursor obtained above, they were ground to a size of about 1 mm and filled into a fixed bed reactor. Then, nickel oxide was reduced using hydrogen at 400 ° C. to prepare an adsorbent in which nickel was supported on a carrier.

Example 2

An adsorbent was prepared in the same manner as in Example 1, except that zeolite Na-X was used instead of silica as a carrier.

Example 3

An adsorbent was prepared in the same manner as in Example 1, except that zeolite Na-Y was used instead of silica as a carrier.

Example 4

An adsorbent was prepared in the same manner as in Example 1, except that gamma alumina was used instead of silica as a carrier.

Example 5

An adsorbent was prepared in the same manner as in Example 1, except that the temperature was raised at a rate of 3 ° C. per minute and dried at 300 ° C. using an electric furnace instead of a domestic microwave oven.

Example 6

An adsorbent was prepared in the same manner as in Example 1, except that air was flowed through an electric furnace to maintain nitrogen at 400 ° C. instead of flowing at air and maintaining at 600 ° C. to allow the organics to be carbonized.

Comparative example

An adsorbent was prepared in the same manner as in Example 1, except that the ethylene glycol and citric acid were fired using an electric furnace immediately after drying using a rotary evaporator.

Experimental Example  : Evaluation of Metal Particle Size and Adsorption Performance of Adsorbent

The adsorbents prepared in Examples 1 to 6 and Comparative Examples were placed in a tubular reactor, and the average size of nickel particles was measured from carbon monoxide adsorption at room temperature.

The adsorbents prepared in Examples 1 to 6 and Comparative Examples were placed in another tubular reactor, and a mixed gas of oxygen, carbon dioxide, and water vapor was passed through the adsorbent at room temperature to analyze gas components that were not adsorbed using gas chromatography. To evaluate the adsorption performance.

The results are shown in Table 1.

carrier Characteristic Metal particle size (nm) Adsorption amount (gas-cc / adsorbent-g) Oxygen carbon dioxide vapor Example 1 Silica 21 4.2 3.9 74 Example 2 Na-X zeolite 24 4.1 4.7 102 Example 3 Na-Y zeolite 26 4.3 4.3 89 Example 4 Alumina 28 4.1 3.6 56 Example 5 Silica Drying: Electric 30 3.8 3.5 70 Example 6 Silica Firing: 400 ℃ nitrogen atmosphere 20 4.1 4.1 66 Comparative example Silica 1) without ethylene glycol and citric acid, 2) firing without drying step 51 2.7 3.0 66

As shown in Table 1, the metal particle size of the adsorbent (Examples 1 to 6) of the present invention is 20 to 30 nm, and the metal particle size (51 nm) of the adsorbent (comparative example) without using ethylene glycol and citric acid. Significantly smaller.

In addition, the adsorption amount of the adsorbent (Examples 1 to 6) of the present invention was found to be 3.8 to 4.3 cc / g of oxygen, 3.6 to 4.7 cc / g of carbon dioxide, and 56 to 102 cc / g of water vapor, and ethylene glycol and citric acid were used. The adsorption amount of the unused adsorbent (comparative example) was 2.7 cc / g of oxygen, 3.0 cc / g of carbon dioxide, and 66 cc / g of water vapor.

Therefore, the adsorbent of the present invention can be efficiently used to purify impurities with high purity such as oxygen, carbon dioxide, and water contained in the inert gas by reducing the metal particle size and improving the dispersibility of the metal.

The method for preparing the adsorbent according to the present invention can be efficiently used to purify impurities, such as oxygen, carbon dioxide, and water, contained in an inert gas with high purity at a time by reducing the metal particle size and improving the dispersibility of the metal.

Claims (9)

1) containing at least one metal component selected from the group consisting of palladium, platinum, silver, nickel and zirconium Adding polyhydroxy alcohol and a chelating agent when the metal precursor is supported on the inorganic carrier, and then heating at a temperature of 25 to 100 ° C. (first step), 2) drying and baking the supported metal precursor at a temperature of 300 to 1000 ° C. (second step), and 3) A method for preparing an adsorbent comprising the step (3) of reducing the supported metal precursor to a metal. The method of claim 1, wherein in the first step, the polyhydroxy alcohol is ethylene glycol or propylene glycol, and the chelating agent is citric acid or oxalic acid. The method of claim 2, wherein the polyhydroxy alcohol is ethylene glycol and the chelating agent is citric acid. delete The method of claim 1, wherein the inorganic carrier in the first step is at least one member selected from the group consisting of silica, alumina, silica alumina, carbon and zeolite. The method of claim 1, wherein a microwave is used for drying and firing in the second step. Adsorption and removal of at least one impurity selected from the group consisting of oxygen, carbon dioxide and water contained in the inert gas using the adsorbent prepared according to any one of claims 1 to 3, 5 and 6. The gas purification method characterized by the above-mentioned. 8. The method of claim 7, wherein the inert gas is nitrogen or helium. delete