KR20080011899A - Catalyzer for cleaning nitrous oxide, production method thereof, and cleaning method of nitrous oxide using it - Google Patents

Abstract

A catalyst for removing nitrous oxide, a method for producing the same, and a method for removing the nitrous oxide using the same are provided to improve the efficiency in removal of the nitrous oxide, by preparing the catalyst using mordenite zeolite as a carrier. A catalyst for removing nitrous oxide is formed by supporting at least one of transition metal and noble metal on a mordenite zeolite carrier. The catalyst is prepared by washing the mordenite zeolite(S300), drying the washed mordenite zeolite(S320), immersing at least one of the transition metal and noble metal in the mordenite(S350), drying the mordenite zeolite(S360), and hardening the dried mordenite zeolite(S370). Further, the transition metal is Fe, and the noble metal is Pd.

Description

Catalyst for removing nitrous oxide, preparation method thereof and method for removing nitrous oxide using the catalyst {Catalyzer for cleaning nitrous oxide, production method etc, and cleaning method of nitrous oxide using it}

1 is a first embodiment illustrating a process of preparing a catalyst according to the present invention;

Figure 2 is a second embodiment showing the manufacturing process of the catalyst according to the present invention,

3 is a third embodiment illustrating a process of preparing a catalyst according to the present invention;

4 is a flowchart showing a procedure for removing nitrous oxide using a catalyst according to the present invention;

5 is a diagram illustrating the removal rate of nitrous oxide according to temperature when removing nitrous oxide using the catalyst according to the present invention;

6 is a view showing a comparison of the reaction temperature when removing nitrous oxide when removing nitrous oxide using the catalyst of the present invention and removing nitrous oxide using a conventional catalyst.

The present invention is to remove nitrous oxide (N₂O), a global warming gas by using a catalyst, and more specifically, a catalyst prepared by supporting a transition metal and a noble metal using a mordenite zeolite as a support, and a method for preparing the same A method for removing nitrous oxide.

In general, two techniques of direct decomposition and selective catalytic reduction are mainly studied for removing nitrous oxide (N₂O) using a catalyst.

In case of direct decomposition, a condition of high temperature of 850 ° C. or higher is required, but the selective catalytic reduction method has an advantage of effectively removing N 2 O around 500 ° C. through a reducing agent injected. In the case of using a zeolite as a catalyst support, when a catalyst for selective catalytic reduction is introduced at a place where N 2 O is generated in a temperature range of 400 to 450 ° C., it is necessary to exhibit maximum activity at a lower temperature. Therefore, it is necessary to develop the catalytic properties for this.

Zeolites, which are usually used as carriers for catalysts, are synthetic zeolites (MFI, MOR, FER, BETA, etc.), and mainly include iron (Fe), copper (Cu), cobalt (Co), and manganese (Mn) as active materials. It has been prepared by loading. In particular, zeolite catalysts have been studied to remove N₂O through selective catalytic reduction method rather than direct decomposition, and N₂O is effectively decomposed in the temperature range of around 450 ℃ by injection of nitrogen-based and hydrocarbon-based reducing agents.

However, the zeolite catalyst should show high activity at temperatures below 400 ℃ when applied to N2O generating plants. Therefore, it is urgent to develop a catalyst that exhibits maximum activity at a temperature of 400 ° C or lower.

The present invention has been made to solve the problems described above, an object of the present invention is to provide a catalyst that can remove N ₂O at a temperature of 400 ℃ or less.

The present invention was completed by finding that the catalyst was prepared using mordenite-type synthetic zeolite as a carrier, unlike the clinoptilolite-type natural zeolite catalyst.

The present invention for achieving the above object provides a catalyst for removing nitrous oxide prepared by supporting any one or more of transition metals and precious metals in the mordenite zeolite support.

The mordenite zeolite carrier preferably has a SiO 2 / Al 2 O 3 ratio of 13 to 90.

The transition metal is supported by ion exchange of the active material iron (Fe), it is preferred that the iron contains 0.01 to 10% by weight.

The noble metal is supported by the impregnation method of palladium (Pd), the palladium preferably contains 0.01 to 5.0% by weight.

The method for preparing a nitrous oxide removing catalyst according to the present invention includes preparing and washing a mordenite zeolite, drying the mordenite zeolite, and converting any one or more of the transition metal and the precious metal into the mordenite zeolite. It provides a method for producing a catalyst for removing nitrous oxide comprising the step of supporting and drying and calcining the mordenite zeolite.

On the other hand, the nitrous oxide removal method according to the present invention comprises the steps of preparing a catalyst for removing nitrous oxide prepared through the above process, injecting a nitrogen-based and hydrocarbon-based reducing agent and the mordenite-type zeolite carrier catalyst and It provides a nitrous oxide removal method comprising the step of removing nitrous oxide using the reducing agent.

In addition, the temperature at which the reducing agent is injected is preferably within 400 ℃.

And, the reducing agent is preferably methane.

Hereinafter, with reference to the drawings will be described in detail the catalyst for removing nitrous oxide, the method for preparing the catalyst and the method for removing nitrous oxide of the present invention.

1 is a first embodiment showing a process for producing a catalyst according to the present invention, FIG. 2 is a second embodiment showing a process for preparing a catalyst according to the present invention, and FIG. 3 is a preparation of a catalyst according to the present invention. The third embodiment shows the process.

Figure 4 is a flow chart illustrating a procedure for removing nitrous oxide using a catalyst according to the present invention, Figure 5 shows the removal rate of nitrous oxide with temperature when removing nitrous oxide using a catalyst according to the present invention. FIG. 6 is a view showing a comparison of reaction temperatures when removing nitrous oxide when removing nitrous oxide using a catalyst of the present invention and removing nitrous oxide when removing nitrous oxide using a conventional catalyst.

Referring to these drawings, in the present invention, a catalyst is prepared by ion-exchanging an active substance iron on a mordenite-type zeolite carrier and then impregnating palladium (Pd), platinum (Pt), or ruthenium (Ru) by impregnation. In addition, it is effective to remove nitrous oxide (N₂O) by using a catalyst and a selective catalytic reduction method supported by two active materials. As a catalyst, mordenite-type zeolite is supported, and a transition metal such as iron (Fe) and two precious metals such as palladium (Pd), platinum (Pt), ruthenium (Ru), etc. are supported as an active material. It is to increase the removal activity of N₂O. In this case, the mordenite zeolite may have a SiO 2 / Al 2 O 3 ratio of about 13 to about 90, and a specific surface area of the zeolite may be 400 to 500 m 2 / g. In addition, iron contains 0.01 to 10% by weight, and palladium includes 0.01 to 5.0% by weight. And, iron and palladium used as an active precursor NO₃ ^- comprises an anion consisting of ^-, Cl ^-, CO ₃ ^- and SO _4.

[First Embodiment]

A first embodiment of the method for preparing a nitrous oxide removal catalyst according to the present invention, as shown in Figure 1, preparing an industrially available mordenite zeolite three times or more washing and drying step (S100, S110, S120) And an ion exchange step (S130) for supporting iron in the mordenite zeolite, and a drying / firing step (S140 and S150).

Referring to FIG. 1, first, mordenite zeolite is first prepared by washing distilled water distilled first with tertiary distilled water passed through an ion exchange filter or a hollow fiber membrane filter, and drying at least three times. (S100, S110, S120)

And, in order to ion exchange iron, which is a transition metal, about 0.01 to 10% by weight of iron is supported on mordenite zeolite for at least 4 hours at a temperature of 70 to 80 ° C. (S130)

Thereafter, mordenite zeolite is dried at a temperature of about 105 to 115 ° C for at least 12 hours, and calcined at 500 ° C or more for 4 hours to produce a Fe-MOR catalyst. (S140, S150)

At this time, as a precursor of a transition metal active material it is iron NO₃ ^- comprises an anion consisting of ^-, Cl ^-, CO ₃ ^- and SO _4.

Second Embodiment

A second embodiment of the method for preparing a catalyst for removing nitrous oxide according to the present invention includes preparing a mordenite zeolite, washing and drying three or more times (S200, S210, and S220) as shown in FIG. Impregnating iron into the zeolite (S230), and drying / baking step (S240, S250) consists of.

Referring to Figure 2, first mordenite zeolite is prepared by washing after three or more times with tertiary distilled water and dried. (S200, S210, S220)

Next, by impregnating the mordenite zeolite using a rotary evaporator so that the noble metal precursor, palladium, is 0.01 to 5.0% by weight, is dried, calcined, and evaporated to form a Pd-MOR catalyst. (S230, S240, S250)

At this time, as a precursor of the active material it is palladium NO₃ ^- comprises an anion consisting of ^-, Cl ^-, CO ₃ ^- and SO _4.

In the second embodiment, the manufacturing process is changed by impregnating the noble metal instead of the ion exchange process under the same conditions as in the first embodiment.

Third Embodiment

According to a third embodiment of the method for preparing a nitrous oxide removal catalyst according to the present invention, as shown in FIG. 3, a step of preparing mordenite zeolite (S310, S320, S330) and supporting iron on mordenite zeolite After the ion exchange step (S330), and after drying, the impregnation step (S340, S350) and the drying / baking step (S360, S370) for supporting the precious metal in the mordenite-type zeolite loaded with iron.

Referring to Figure 3, first, the mordenite zeolite is prepared by washing at least three times in tertiary distilled water and then drying. (S300, S310, S320)

For ion exchange of iron, a transition metal, about 0.01 to 10% by weight of iron is supported on mordenite zeolite for at least 4 hours at a temperature of 70 to 80 ° C. (S330)

After that, the mordenite zeolite is dried for 12 hours or more at a temperature of about 105 to 115 ° C. (S340)

Next, the iron-supported mordenite zeolite was impregnated with palladium using a rotary evaporator, and then dried at a temperature of about 105 to 115 ° C. for at least 12 hours, and at 500 ° C. or higher for 4 hours. The above baking was performed to prepare Pd-Fe-MOR catalyst. (S350, S360, S370)

At this time, iron and palladium as a precursor of the active material NO₃ ^- comprises an anion consisting of ^-, Cl ^-, CO ₃ ^- and SO _4.

As described above, in the third embodiment, the manufacturing process is changed to perform both the ion exchange process and the impregnation of the noble metal under the same conditions as the first and second embodiments.

[How to remove nitrous oxide]

As described above, the procedure for removing nitrous oxide (N ₂ O) by a selective catalytic reduction method using a mordenite-type zeolite carrier catalyst prepared according to the present invention as shown in FIG. 4 is performed at least three times in tertiary distilled water. Preparing a mordenite zeolite by washing and drying to prepare a mordenite zeolite, and preparing a mordenite zeolite carrier catalyst by supporting iron, which is a transition metal, and drying / firing (S400); and a prepared mordenite zeolite carrier catalyst and a reducing agent It comprises a step (S410) to remove the nitrous oxide using. At this time, the reducing agent to be injected for the selective catalytic reduction reaction is nitrogen-based and hydrocarbon-based (CH ₄ , NH ₃ , C ₃ H ₈ Etc.) a reducing agent can be used.

Comparative Example

Nitrogen oxides were added to the Fe-MOR catalyst supporting or impregnating iron and palladium, respectively, to the mordenite zeolite, the Pd-MOR catalyst, and the Pd-Fe-MOR catalyst supporting iron and palladium two kinds of metals. The removal rate was tested.

Reagents such as mordenite zeolite, iron, and palladium, a catalyst manufacturing device (ion exchange and impregnation), and an active experimental reaction device (gas injection device, reactor, gas analyzer) are prepared.

The experiment was conducted by adjusting the space velocity to 5,000 ~ 20,000 / hr and the concentration of O ₂ to 0.5 ~ 2%. The reaction gas was injected at a constant concentration through a gas flow meter. In addition, the reducing agent injected for the selective catalytic reduction reaction is nitrogen-based and hydrocarbon-based (CH ₄ , NH ₃ , C ₃ H ₈ Etc.) were used. In particular, in the present invention, methane is used as a reducing agent, and the concentration of the reducing agent is injected by adjusting the reaction gas with nitrous oxide and a mole ratio of 1: 1.

5 is a Fe-MOR catalyst in which iron is supported on a mordenite zeolite support, a Pd-MOR catalyst in which palladium is impregnated in a mordenite zeolite support, and iron is supported on a mordenite zeolite support, As a result of comparing the nitrous oxide removal activity of the Pd-Fe-MOR catalyst impregnated with palladium, the removal rate of nitrous oxide was found to be 35, 40 and 85%, respectively, at a reaction temperature of 350 ° C.

Therefore, it can be seen that nitrous oxide can be removed under the reaction temperature of 350 ° C., and in particular, the activity of the Pd-Fe-MOR catalyst is greatly increased.

Generally, catalysts are prepared by injecting a large number of active materials or by adding a large amount of the active substance. However, in the case of the catalyst carrying both the experimental transition transition metal and the noble metal at the same time, the inventors have found that the catalytic activity is superior at a low temperature of 350 ° C. over the catalysts carried one by one.

6 is a nitrous oxide removal amount by a catalyst supporting iron and palladium on a natural zeolite support according to the temperature, and as shown in FIG. 5 by a catalyst supporting iron and palladium on a mordenite zeolite support As a drawing showing the comparison of nitrous oxide removal amount, it can be seen that a catalyst carrying iron and palladium on a natural zeolite support can expect nitrous oxide removal rate similar to that of a mordenite zeolite catalyst at high temperature, that is, 350 to 500 ° C. Can be.

While the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated.

As described above, the mordenite zeolite carrier catalyst of the present invention has an advantage of increasing the removal rate of nitrous oxide at a temperature of about 350 ° C.

In addition, since the reaction temperature to remove the nitrous oxide can be lowered, there is an advantage that the energy of various combustion industrial equipment can be reduced.

Claims (14)

A nitrous oxide removal catalyst prepared by supporting any one or more of transition metals and precious metals on a mordenite-type zeolite carrier. The method according to claim 1, The mordenite-type zeolite carrier has a SiO₂ / Al₂O₃ ratio of 13 to 90, characterized in that the nitrous oxide removal catalyst. The method according to claim 2, The transition metal is nitrous oxide removal catalyst, characterized in that the active material iron (Fe). The method according to claim 3, The iron is nitrous oxide removal catalyst, characterized in that containing 0.01 to 10% by weight. The method according to claim 2, The noble metal is nitrous oxide removal catalyst, characterized in that palladium (Pd). The method according to claim 5, The palladium is nitrous oxide removal catalyst, characterized in that containing 0.01 to 5.0% by weight. Preparing and washing the mordenite zeolite; Drying the mordenite zeolite; Supporting at least one of transition metal and precious metal in the mordenite zeolite; And A method for preparing a catalyst for nitrous oxide removal comprising drying and firing the mordenite zeolite. The method according to claim 7, The transition metal is nitrous oxide removal catalyst, characterized in that the active material iron (Fe). The method according to claim 8, The iron is nitrous oxide removal catalyst, characterized in that containing 0.01 to 10% by weight. The method according to claim 7, The noble metal is nitrous oxide removal catalyst, characterized in that palladium (Pd). The method according to claim 10, The palladium is nitrous oxide removal catalyst, characterized in that containing 0.01 to 5.0% by weight. Preparing a mordenite zeolite carrier catalyst according to claims 1 to 11; Injecting nitrogen-based and hydrocarbon-based reducing agents; And Nitrous oxide removal method comprising the step of removing nitrous oxide using the mordenite-type zeolite carrier catalyst and the reducing agent. The method according to claim 12, Nitrous oxide removal method, characterized in that the temperature at which the reducing agent is injected within 400 ℃. The method according to claim 13, The reducing agent is nitrous oxide removal method, characterized in that methane.

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