KR19980051229A - Method for preparing gold catalyst using adsorption precipitation method and method for removing carbon monoxide using the same - Google Patents

Abstract

The present invention relates to a method for preparing a gold catalyst using an adsorption precipitation method and a method for removing carbon monoxide using the same, wherein a metal oxide promoter is added to an aqueous solution of a metal oxide and then the pH is slightly raised to adsorb the gold to the metal oxide, A method for preparing a gold catalyst for removing carbon monoxide by filtration and water rinsing several times with hot distilled water to remove precipitates and drying in air and then calcining the dried product in an air atmosphere; Oxidizing carbon monoxide with oxygen to convert it to carbon dioxide and removing it.

In the present invention, the gold catalyst produced by carrying a small amount of gold at a low firing temperature while using an adsorption precipitation method has excellent conversion of carbon monoxide even in a gaseous state including water and at room temperature.

Description

Method for preparing gold catalyst using adsorption precipitation method and method for removing carbon monoxide using the same

The present invention relates to a method for preparing gold catalysts using adsorption precipitation and a method for removing carbon monoxide using the same. More particularly, the present invention relates to a method for adsorbing gold on a metal oxide using an adsorption precipitation method, And a method for oxidizing carbon monoxide at low temperature by using the catalyst.

Carbon monoxide is a colorless, odorless, toxic material that is produced by incomplete combustion in transportation or heating, and is one of the major air pollutants along with SOx and NOx.

In the case of a CO ₂ laser device, CO and oxygen are generated by the decomposition of CO ₂ , which shortens the life of the device and must be converted back to CO ₂ .

Most of the above CO removal methods are performed by oxidation reaction with oxygen existing in the exhaust gas using a catalyst. In this case, the most used catalyst is a catalyst in which a noble metal such as platinum (Pt) or palladium (Pd) is supported on a support such as alumina (Al ₂ O ₃ ).

According to Journal of Catalysis, 87, p152-162, 1984, carbon monoxide is removed at 230-300 ° C using a catalyst in which platinum and palladium are supported on alumina or ceria (CeO ₂ ) / alumina.

In this case, the metal oxide catalysts are known to exhibit activity in the oxidation reaction of carbon monoxide at lower temperatures, while the noble metals used require high reaction temperatures. For example, in DD 298035, carbon monoxide is removed at room temperature using a Hopcalite catalyst comprising copper, manganese, cobalt and silver.

However, when the gold catalyst is prepared by the coprecipitation method as described above, since gold is surrounded by the catalyst, only a certain amount of the used gold is exposed on the surface, and the reaction active site is relatively lowered.

Haruta et al. Disclose a method of preparing a catalyst by supporting gold on an alkaline earth metal oxide such as Fe ₂ O ₃ by using an adsorption precipitation method and using the same to remove carbon monoxide at room temperature. In particular, a calcination temperature of 300-400 (Journal of Catalysis, 144, 175-192, 1993). ≪ tb >< TABLE >

In this case, gold and cocatalyst were used in a ratio of 1:19 to prepare the gold catalyst. In this case, gold is expensive and there is a problem that a part of gold is removed as a precipitate by using an adsorption precipitation method.

Accordingly, an object of the present invention is to provide a method for producing a gold catalyst having improved removal efficiency of carbon monoxide even when a small amount of gold is supported at a low firing temperature while using an adsorption precipitation method.

In one aspect of the present invention, there is provided a method for producing a metal oxide, comprising the steps of: adding a metal oxide promoter to an aqueous solution of a gold particle and gradually adding a basic solution to adsorb the metal to the metal oxide while raising the pH; Filtering, washing and drying, and calcining the dried product at 100-300 占 폚 under an atmospheric atmosphere.

According to a second aspect of the present invention, there is provided a method for removing carbon dioxide by oxidizing carbon monoxide in an exhaust gas containing water at a temperature of 30-500 DEG C in the presence of a gold catalyst produced by the first aspect.

Hereinafter, the present invention will be described in detail.

In the present invention, a gold catalyst is prepared by adding a metal oxide to an aqueous solution of a gold sphere and slowly adding a basic solution to increase the pH of the solution, adsorbing the gold to the metal oxide, and controlling the sintering temperature.

The metal oxide used as a promoter in the present invention is prepared by the general precipitation method. Oxides of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Be, Mg, Zr, Mo, W and Sn were used as co-catalysts.

The cash specific aqueous solution of gold was used as 0.01-20% by weight, based on the amount of catalyst that was used for the hydrate HAuC1 ₄ · 3H ₂ O dissolved in the HAuCl ₄ in secondary distilled water, to prepare.

The metal oxide was added to the aqueous solution of the gold particles and then gold was added to the surface of the metal oxide by slightly increasing the pH by adding one or two drops of 0.1 M NaOH or Na ₂ CO ₃ as a basic solution.

The adsorbed material was aged for about 1 hour and filtered.

Filtered, washed with hot distilled water several times to remove precipitates, and then sufficiently dried in air at 80 ° C for about 12 hours.

The dried product was calcined at 100-300 ° C in air to prepare a gold catalyst for removing carbon monoxide. The firing temperature is an important pretreatment factor in the production of the gold catalyst. When the firing temperature is higher than 300 ° C., the size and dispersion of the gold catalyst particles are different from each other, and thus gold in the gold precursor solution is required to be excessively large .

Using the gold catalyst thus prepared, the gas containing moisture was oxidized at 30-500 ° C to remove carbon monoxide by converting it to carbon dioxide.

According to the method of the present invention, a gold catalyst can be produced by carrying a small amount of gold while firing at a low temperature while using an adsorption precipitation method. In addition, the removal efficiency of carbon monoxide in the presence of the gold catalyst is almost 100%.

Hereinafter, the present invention will be described in detail with reference to examples.

[Example]

[Example 1-2]

The CO removal efficiencies of the gold catalyst of the present invention prepared by the adsorption precipitation method and the gold catalyst prepared by the conventional coprecipitation method are compared with those of Table 1 below.

As the co-catalyst, Fe ₂ O ₃ oxide was added to the gold solution and the gold was adsorbed by adding a drop of 0.1 M NaOH solution. The adsorbate was filtered and dried, and then calcined at 300 ° C in air to prepare a gold catalyst.

The prepared gold catalyst was oxidized at a reaction temperature of 50 ° C. with 1% carbon monoxide, 2.3% water and air as a reaction gas, and the space velocity was 90,000 L / kg-cat / hr.

The carbon monoxide removal rate was measured by gas chromatography (GC).

As shown in the above table, when the adsorption precipitation method was used, the conversion of carbon monoxide was increased by 54%, especially the conversion efficiency to carbon dioxide was 100%.

[Example 3-17]

The CO removal rate in the gold catalyst prepared by the co-catalyst

The mixed solution was prepared by adding metal oxide as a co-catalyst to gold solution (HAuCl ₄ .3H ₂ O) solution. Then, one or two drops of 0.1M MaOH solution was added to raise the pH to adsorb the gold to the metal oxide And then washed with filtration and hot distilled water to remove the precipitate, followed by drying at 80 ° C in the air and calcining at 100 ° C under atmospheric conditions to prepare a catalyst.

At this time, the gold in the aqueous solution of the gold spheres was 1% by weight and oxidized at 30 ° C using 1% carbon monoxide / air as the reaction gas, and the space velocity was 20,000 L / kg-cat / hr.

The carbon monoxide removal rate of the gold catalyst was measured by gas chromatography in the case where the gold catalyst was prepared using each metal oxide as a promoter and the cocatalyst was different.

As shown in the above table, the conversion of carbon monoxide measured by the co-catalyst was 100% using the adsorption precipitation method and firing at 100 ° C. In this case, the carbon monoxide removal efficiency was excellent even at a low firing temperature, and the effect was excellent for all the above catalysts.

[Examples 18-20]

CO removal rate by reaction time according to calcination temperature of catalyst

The catalyst was prepared in the same manner as in Example 6 except that the firing temperature of the catalyst was changed, and the carbon monoxide removal rate by the reaction time was measured by gas chromatography. The results are shown in Table 3 below.

As shown in the above table, the CO removal rate was excellent not only at 1 hour but also at 20 hours after firing at 100-300 ° C. As time passes, the reaction activity decreases slightly depending on the firing temperature because the particle size of the surface exposed gold becomes larger as the firing temperature increases.

[Examples 21-24]

CO removal rate according to oxidation temperature of catalyst

A catalyst was prepared in the same manner as in Example 16, except that the temperature for oxidizing carbon monoxide was changed using a catalyst. The measured carbon monoxide removal rates are shown in Table 4 below.

As shown in the above table, carbon monoxide was preferably oxidized in the range of 50-500 ° C.

[Examples 25-39]

CO removal rate according to the content of gold

The removal rate of carbon monoxide was measured in the same manner as in Example 1 except that the weight ratio of the main catalyst was changed. The results are shown in Table 5 below.

As shown in the table, when carbon was used as the main catalyst in an amount of 0.01-20.0 wt% and the metal oxide of each promoter was used in an amount of 80.0-99.9 wt%, the removal rates of carbon monoxide were all appropriate.

In the present invention, the gold catalyst produced by carrying a small amount of gold at a low firing temperature while using the adsorption precipitation method had a very excellent conversion of carbon monoxide even in a gaseous state including water and at room temperature.

Claims (4)

Adding a metal oxide promoter to the aqueous solution of a gold particle and gradually adding a basic solution to gradually raise the pH to adsorb the gold to the metal oxide; aging the gold adsorbed on the metal oxide, And a step of calcining the dried product at 100-300 占 폚 in an atmospheric atmosphere to prepare a gold catalyst using an adsorption precipitation method The method according to claim 1, wherein the content of gold in the gold-supported gold catalyst is 0.1 to 20 wt% The method according to claim 1, wherein an oxide of Ti, Vr, Cr, Mn, Fe, Co, Ni, Cu, Zn, Be, Mg, Zr, Mo, A method for removing carbon monoxide using a gold catalyst comprising removing carbon monoxide by oxidizing an exhaust gas containing moisture in the presence of the gold catalyst produced according to claim 1 at a temperature of 30-500 ° C