KR100651785B1 - Oxidation catalyst for carbon monoxide removal and carbon monoxide removal method using the same - Google Patents

Abstract

An oxidation catalyst comprising an Mn-Ce-Zr-Ti oxide support for removing carbon monoxide, which improves reactivity, and has high reaction activity when removing CO by oxidation reaction even in the presence of alkaline materials as well as sulfur oxides, and a method of removing carbon monoxide using the same are provided. A catalyst for removing carbon monoxide comprises: an Mn-Ce-Zr-Ti oxide support; and active materials including Rh and Pt supported on the support. The catalyst contains 0.01 to 5 wt.% of Rh based on the total catalyst weight. The catalyst contains 0.01 to 5 wt.% of Pt based on the total catalyst weight. A method of removing carbon monoxide comprises the process of contacting a gas containing carbon monoxide and oxygen with a catalyst for removing carbon monoxide comprising an Mn-Ce-Zr-Ti oxide support, and active materials including Rh and Pt supported on the support. The contacting process is performed at a temperature of 180 to 500 deg.C.

Description

OXIDATION CATALYST FOR REMOVING CARBON MONOXIDE AND METHOD OF REMOVING CARBON MONOXIDE USING SAME}

[Industrial use]

The present invention relates to an oxidation catalyst for removing carbon monoxide (CO) and a method for removing carbon monoxide using the same. It is about.

[Prior art]

In general, carbon monoxide emitted from exhaust gases such as boilers, incinerators or combustion furnaces is a toxic substance and should be removed. Most of the methods used to remove such CO are oxidized to remove oxygen and CO present in the exhaust gas using a catalyst. However, incinerator flue-gases and in particular, flue-gases generated in steel mills include sulfur oxides and dusts, and these dust components often contain alkaline components in the flue-gases. The presence of such sulfur oxides or alkali components contained in the flue gas poisons the catalyst used to remove CO, thereby degrading the activity of the catalyst.

Various catalysts have been used for the oxidation of CO. The most commonly used catalysts are those in which a noble metal such as platinum (Pt) or palladium (Pd) is supported on a metal oxide support such as Al ₂ O ₃ or SnO ₂ . For example, European Patent EP 0408528 arc in the use of the catalyst impregnated with Pt in the SnO ₂ has been fully remove CO at about 150 ℃, Soviet Patent SU 1695979 call using a catalyst impregnated with Pd on Al ₂ O ₃ 110 To 160 ° C. In "Journal of Catalysis, 87, pp. 152-162, 1984", CO is removed at 230 to 300 ° C with a catalyst in which Pt or Pd is supported on Al ₂ O ₃ or CeO ₂ / Al ₂ O ₃ . In addition, Japanese Patent Application Laid-open No. Hei 1-94945 removes CO at room temperature with a catalyst in which gold (Au) is supported on a metal oxide such as Fe ₂ O ₃ .

In addition, a catalyst made of a metal oxide is also used. In the USSR patent SU 1837948, a catalyst consisting of Y ₂ O ₃ , BaO and CuO is used to remove CO at 95 to 135 ° C. In addition, "Ind. Eng. Chem. Prod. Res. Dev., 22, pp. 396-401, 1983" uses a metal oxide consisting of Cu and Cr to remove CO above 200 ℃, "Journal of Catalysis , 153, pp. 304-316, 1995 "remove CO at about 100 ° C in a catalyst consisting of oxides such as Cu, Ce, and La. In addition, there is a catalyst called Hopcalite. For example, in German Patent 298035, an oxide catalyst composed of Cu, Mn, Co, and Ag is used to remove CO at room temperature.

However, most of the above-described CO removal catalysts are known to have a significantly lower catalytic activity when sulfur oxides are present in the reaction gas. For example, "Appl. Catal. B: Environmental, 4, pp. 105-140, 1994" describes sulfur oxides in catalysts in which Pt, Pd, Rh, and Ce, which are commonly used as catalysts for automobile flue gas purification, are supported on Al ₂ O ₃ . In this non-containing gas, CO may be removed from about 225 to 250 ° C, but when 20 ppm of sulfur oxide is included, CO may be removed only when it is 295 to 320 ° C or more. In addition, metal oxide catalysts are also known to be less poisonous to sulfur oxides than to noble metal catalysts, and are greatly inferior in activity.

The present invention is to solve the above-mentioned problems, an object of the present invention is to improve the reactivity, the oxidation catalyst for removing carbon monoxide having a high reaction activity to remove CO by the oxidation reaction in the presence of alkali components as well as sulfur oxides. To provide.

Another object of the present invention is to provide a method for removing carbon monoxide using the catalyst.

In order to achieve the above object, the present invention provides an oxidation catalyst for removing carbon monoxide comprising an Mn-Ce-Zr-Ti oxide carrier and an active material comprising Rh and Pt supported on the carrier.

The present invention also provides a carbon monoxide comprising a step of contacting a carbon monoxide removal catalyst comprising a Mn-Ce-Zr-Ti oxide carrier and an active substance comprising Rh and Pt supported on the carrier, and a gas containing carbon monoxide and oxygen. Provide a removal method. It is preferable to perform the said contact process at 180-500 degreeC.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The oxidation catalyst for removing carbon monoxide of the present invention includes an Mn-Ce-Zr-Ti oxide carrier and an active material including Rh and Pt supported on the carrier.

The amount of the active substance supported on the carrier is preferably 0.01 to 5% by weight and 0.01 to 5% by weight of Pt based on the total weight of the catalyst. The content of the Rh and Pt metals in the catalyst should be kept as low as possible because these metals are very expensive. However, when the metal content is too low, the catalytic activity is lowered, and when the metal content is high, the CO removal rate is not significantly increased, and the catalyst is very expensive.

The catalyst of the present invention has almost no poisoning problem caused by sulfur oxides or alkaline materials, and thus can effectively remove carbon monoxide even if such materials are present.

The catalyst according to the present invention is prepared as follows.

First, Mn-Ce-Zr-Ti oxide as a carrier adds a Mn compound to a solvent to prepare a Mn solution. The solvent may be any material capable of dissolving selected metal compounds such as water and alcohol.

Zr compound, Ce compound and Ti compound are added to the Mn solution.

As the Mn compound, any dissolved in a solvent used may be used, and representative examples thereof may include Mn (NO ₃ ), (CH ₃ CO ₂ ) ₂ Mn, MnCl ₂ , and the like, and ZrO ₂ as a Zr compound. , ZrOCl ₂ , ZrCl ₄ and the like can be used. In addition, Ce (OH) ₄ , (CH ₃ CO ₂ ) ₃ Ce, or Ce (NO ₃ ) ₃ may be used as the Ce compound, and TiO ₂ is preferably used as the Ti compound. At this time, the mixing ratio of Mn, Zr, Ce and Ti is preferably 0.5 to 5: 1 to 10: 0.5 to 2: 5 to 10 weight ratio.

Subsequently, an alkali solution is added to the obtained mixture to adjust pH so that Mn, Ce, Zr and Ti precipitates are produced, and the resulting precipitate is filtered and dried to prepare Mn-Ce-Zr-Ti oxide as a carrier. The alkali solution may be NH ₄ OH, Na ₂ CO ₃ or NaOH. At this time, the pH is preferably adjusted to 7 to 11.

The Rh compound and the Pt compound are dissolved in a solvent at a desired ratio to prepare a Rh-Pt solution. As the solvent, water, alcohol or the like can be used. Mn-Ce-Zr-Ti oxide which is a carrier prepared in the Rh-Pt solution is immersed and dried. RhCl ₃ , Rh (NO ₃ ) _3, etc. may be used as the Rh compound, and PtCl ₄ , H ₂ PtCl ₆ .xH ₂ O, or the like may be used as the Pt compound.

The obtained mixture was heat-treated to prepare a catalyst in which Rh and Pt were supported on Mn-Ce-Zr-Ti oxide. The heat treatment process is preferably performed for 2 to 24 hours at 300 to 500 ℃.

On the catalyst prepared according to this process, carbon monoxide can be removed by oxidation with CO ₂ by reaction with oxygen even in the presence of sulfur oxides or alkali components.

The method for removing carbon monoxide using the catalyst of the present invention includes the step of contacting a gas containing carbon monoxide and oxygen with the catalyst of the present invention. According to this contacting process, carbon monoxide reacts with oxygen to convert into carbon dioxide. At this time, the catalyst of the present invention does not generate poisoning due to sulfur oxides or alkali components, and even if such components are included, the oxidation reaction of carbon monoxide may occur effectively.

In the present invention, the contact process is preferably carried out at 180 to 500 ℃. When the contacting process temperature is less than 180 ° C, the activity of the catalyst does not appear sufficiently, so the CO removal rate is lowered. When the contacting process temperature exceeds 500 ° C, the particle size of the metal components in the catalyst increases due to the temperature, thereby lowering the activity of the catalyst.

Hereinafter, embodiments of the present invention will be described in detail.

In the following examples the constituents of the reaction gas consist of 1% CO, 4% water, 100 ppm SO ₂ and the remainder air. The reaction was carried out under the conditions of a space velocity of 300,000 ml / hr / gcat (catalyst weight) at atmospheric pressure, where the space velocity is expressed in unit time, the volume of the reactor per unit catalyst weight.

Example 1-5

60 g of Mn (NO ₃ ) .xH ₂ O was dissolved in water to prepare a Mn solution, and 50 g of ZrO ₂ , 20 g of Ce (OH) _4, and 150 g of TiO ₂ were added to the Mn solution and mixed well.

NH ₄ OH solution was added to the resulting mixture until the pH was 9 so that the Mn component in the solution precipitated. The precipitate was dried after filtration.

The dried sample was heated at 500 ° C. for 3 hours to prepare a Mn-Ce-Zr-Ti oxide carrier.

Mn-Ce-Zr-Ti was dissolved in distilled water after RhCl ₃ and H ₂ PtCl ₆ · xH ₂ O were dissolved so that Rh and Pt were 0.5 wt% and 1 wt%, respectively, based on the Mn-Ce-Zr-Ti oxide carrier. Oxide was immersed in this solution to prepare a slurry.

The slurry thus prepared was heated while stirring well to evaporate the water in the solution, dried in a drier of about 110 ° C. in an air atmosphere, and heat treated at 500 ° C. to prepare a catalyst.

0.5% Rh-1% Pt / Mn-Ce-Zr-Ti catalyst having 0.5% by weight and 1% by weight of Pt thus prepared was placed in a fixed bed reactor having an internal diameter of 1cm, and the space velocity was 300,000 ml / hr. A reaction gas containing 100 ppm of SO ₂ was poured into a gas of 1% CO / 4% H ₂ O / air at / gcat and contacted with Examples 1 to 5 catalysts. At this time, the reaction temperature was changed while changing from 150 degreeC to 500 degreeC.

Table 1 shows the removal rate of CO according to the reaction temperature, and 100% of the CO was removed at the reaction temperature of about 230 ° C. or more.

Reaction temperature (℃) CO removal rate (%) Example 1 150 35 Example 2 180 84 Example 3 230 100 Example 4 300 100 Example 5 500 100

Example 6-10

In the same manner as in Example 1-5, RhCl ₃ and H ₂ PtCl ₆ .xH ₂ O were dissolved in distilled water according to the amount of Rh and Pt required, and Rh and Pt were supported on the Mn-Ce-Zr-Ti oxide carrier. Catalyst was prepared. The catalysts thus prepared were reacted at a reaction temperature of 200 ° C. under the same conditions as in Example 1-5.

Table 2 below shows the removal rate of CO for the catalysts as Comparative Examples 1 and 2, which are 1% Pd / Al ₂ O ₃ and 0.5% Rh-1% Pt / TiO ₂ catalysts.

catalyst CO removal rate (%) Example 6 0.01% Rh-0.5% Pt / Mn-Ce-Zr-Ti 69 Example 7 1% Rh-0.1% Pt / Mn-Ce-Zr-Ti 86 Example 8 1% Rh-0.5% Pt / Mn-Ce-Zr-Ti 94 Example 9 5% Rh-0.01% Pt / Mn-Ce-Zr-Ti 100 Example 10 0.01% Rh-5% Pt / Mn-Ce-Zr-Ti 100 Comparative Example 1 1% Pd / Al ₂ O ₃ 19 Comparative Example 2 0.5% Rh-1% Pt / TiO ₂ 45

As shown in Table 2, it can be seen that the CO removal rate of the catalysts of Examples 6 to 10 is much better than Comparative Examples 1 and 2.

Example 11

A solution of KCl dissolved in water was added to the catalyst of Example 1-5, and dried so that the KCl content was 5% of the catalyst.

The reaction was fixed at 250 ° C. under the same conditions as in Example 1-5 using the dried catalyst sample. As a comparative example, the results according to the reaction time were shown in Table 3 below using a sample in which 5% KCl was added to 1% Pd / Al ₂ O ₃ and 0.5% Rh-1% Pt / TiO ₂ catalyst.

catalyst Response time (hr) CO removal rate (%) Example 11 0.5% Rh-1% Pt / Mn-Ce-Zr-Ti One 100 16 99 24 99 45 98 Comparative Example 1 1% Pd / Al ₂ O ₃ One 84 16 37 24 23 Comparative Example 2 0.5% Rh-1% Pt / TiO ₂ One 99 16 92 24 83

As shown in Table 3, the catalyst of Example 11 exhibited 98% of the CO removal rate even after 45 hours of reaction as well as the CO removal rate, whereas in the case of Comparative Examples 1 and 2, the initial CO removal rate was also shown in Example 11 It can be seen that the CO removal rate is remarkably lowered even when the reaction is slightly lower than that for only 24 hours.

As described above, the oxidation catalyst for removing carbon monoxide of the present invention does not have a catalyst poisoning problem caused by sulfur oxides or alkaline substances and thus can remove carbon monoxide more effectively.

Claims (5)

Mn-Ce-Zr-Ti oxide carriers; And Active substance comprising Rh and Pt supported on the carrier Carbon monoxide removal catalyst comprising a. According to claim 1, The Rh content is a carbon monoxide removal catalyst of 0.01 to 5% by weight based on the total weight of the catalyst. According to claim 1, The Pt content is a carbon monoxide removal catalyst of 0.01 to 5% by weight based on the total weight of the catalyst. A carbon monoxide removal catalyst comprising an Mn-Ce-Zr-Ti oxide carrier and an active substance containing Rh and Pt supported thereon is brought into contact with a gas containing carbon monoxide and oxygen. Carbon monoxide removal method containing a process. The method of claim 4, wherein The method of removing the carbon monoxide is carried out at 180 to 500 ℃.