KR20180113687A - Manufacturing method of the catalyst for the purification of exhaust gas - Google Patents

Abstract

The present invention relates to a method for producing an exhaust gas purifying catalyst. More specifically, the present invention relates to a method for producing a catalyst to remove nitrogen oxide having high resistance to sulfur dioxide. To this end, the method comprises the following steps: a) preparing a first solution mixture, adding the solution mixture to a reactor, and aging the same; b) cooling the first solution mixture, and washing and firing obtained gel to prepare a manganese oxide-copper oxide carrier; c) heating the solution mixture to prepare a second solution mixture in which the gel is formed, adding the same to the reactor, and aging the same; and d) after cooling the second solution mixture, washing and firing the obtained gel to prepare a manganese oxide-copper oxide-cobalt oxide carrier.

Description

TECHNICAL FIELD [0001] The present invention relates to a catalyst for purifying an exhaust gas,

The present invention relates to a method for producing an exhaust gas purifying catalyst.

More specifically, the present invention relates to a method for preparing a catalyst for removing nitrogen oxides having high resistance to sulfur dioxide.

According to the industrialization, the representative air pollutants (NOx) and sulfur oxides (NOx) and sulfur oxides emitted from various combustion processes and pyrolysis processes should be removed to a certain concentration or less due to environmental risks.

As a method for removing such nitrogen oxides (NOx), selective catalytic reduction (SCR) is generally used. This method is a method of decomposing by reacting with a reducing agent such as ammonia at a high temperature of about 300 to 350 ° C by using a catalyst of a metal oxide containing vanadium or titania as a main component. The method is relatively efficient, There is a disadvantage that the temperature is at least 300 캜 or higher. In addition, sulfur oxides together with nitrogen oxides are generated in the combustion exhaust gas. This sulfur oxide reacts with ammonia to generate ammonium sulfate. When the ammonium sulfate is precipitated in the exhaust passage of the exhaust system, the exhaust gas processing flow path is closed, so that the nitrogen oxide removal efficiency is greatly lowered.

In order to solve this problem, the present applicant has developed a copper-manganese oxide catalyst in Korean Patent No. 10-0887545. However, copper and manganese oxides exhibit very high adsorption characteristics even at relatively low temperatures with respect to nitrogen oxides, The width of the region is narrow. In order to overcome this problem, there have been attempts to remove nitrogen oxides in a relatively wide temperature range by adding other metals, but in this case, the removal performance of nitrogen oxides has been reduced. In addition, the manganese-based manganese oxide catalyst has a disadvantage that it is not highly resistant to sulfur dioxide (SO ₂ ).

Korean Patent No. 10-0887545

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and it is an object of the present invention to provide a method of manufacturing a catalyst for purification of exhaust gas having high durability against sulfur dioxide (SO ₂ ) and increased removal efficiency of nitrogen oxides (NO x). More specifically, an object of the present invention as well as a conventional large specific surface area compared with the nitrogen oxide (NOx) removal catalyst, much catalyst activator more on the surface (active site) by having as small a degree purifying an exhaust gas having a high resistance to SO ₂ And a method for producing the catalyst.

The invention also expand further the low temperature region, the temperature region than the available Specifically, as well as NOx removal efficiency in the 150 to 250 ℃, used, including cobalt, based on the manganese and copper to 300 ℃, sulfur dioxide (SO ₂₎ In order to further improve the durability of the battery. Further, by using zeolite calcined in an inert gas atmosphere as a carrier, not only a usable temperature range can be widened, but also the selectivity of nitrogen oxide is further improved, and the removal efficiency of nitrogen oxide is further improved by the amount of reducing agent equivalent to the conventional And an object of the present invention is to provide a catalyst for purification of exhaust gas with high efficiency.

Still another object of the present invention is to provide a method for producing a catalyst for purification of exhaust gas, which is simple in production process and low in manufacturing cost and easy to mass-produce.

In order to achieve the above object,

a) heating a mixed solution of manganese salt, copper salt, base and distilled water to prepare a first mixed solution in which a gel is formed, charging the mixture into a reactor, and aging the mixture in a state of being pressurized with air;

b) adding distilled water to the reactor while reducing the pressure of the reactor to normal pressure to cool the first mixed solution, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide carrier;

c) heating a mixture of the manganese oxide-copper oxide carrier, cobalt salt, base, and distilled water to prepare a second mixed solution having a gel, adding the mixture to the reactor, and aging the mixture while pressurizing with air; And

d) cooling the second mixed solution by adding distilled water while lowering the pressure of the reactor to normal pressure, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide-cobalt oxide carrier;

And a method for producing the catalyst for purification of exhaust gas.

The present invention can economically produce a catalyst for purification of exhaust gas having excellent nitrogen oxide removal activity and excellent resistance to sulfur dioxide (SO ₂ ) at not only a low temperature range of 150 to 250 ° C but also a high temperature range of 250 ° C to 300 ° C have.

Specifically, the present invention can economically produce an exhaust gas purifying catalyst having a removal efficiency of a nitrogen compound at 150 ° C of 50% or more and a removal efficiency of a nitrogen compound at 210 to 300 ° C of 90% or more.

1 is a device structure used in the aging step of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described more fully hereinafter with reference to the accompanying drawings, It should be understood, however, that the invention is not limited thereto and that various changes and modifications may be made without departing from the spirit and scope of the invention.

Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention is merely intended to effectively describe a specific embodiment and is not intended to limit the invention.

Also, the singular forms as used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The inventors of the present invention prepared a first supported catalyst using manganese salt and copper salt and further reacted with the first supported catalyst using a small amount of cobalt salt as compared with manganese salt and copper salt to prepare a ternary catalyst The removal efficiency of the nitric acid compound is further improved as compared with the catalyst in which the catalyst and the manganese salt, the copper salt and the cobalt salt are simultaneously reacted with each other using the conventional manganese salt and copper salt, and the usable temperature range of the catalyst is 150 to 300 ° C And the durability against sulfur dioxide (SO ₂ ) can be further improved even when it is used in a small amount, and the removal efficiency of nitrogen oxides can be improved, thereby completing the present invention.

In addition, during the process of forming the gel, the product was aged at high temperature and high pressure, and after the aging process, the pressure was released to normal pressure and a large amount of distilled water at room temperature was added thereto to quench the product. And the specific surface area are increased, thereby completing the present invention. The specific surface area of the catalyst prepared according to the present invention has a value of 200 m 2 / g or more, preferably 230 m 2 / g or more in terms of the BET measurement method, and the upper limit thereof is 1000 m 2 / g or less. On the other hand, in the case of the catalyst prepared from the conventional atmospheric reaction, the specific surface area by BET measurement is in the range of 130 to 180 m 2 / g and the catalytic activity at low temperature is very low.

In addition, when zeolite calcined in an inert gas atmosphere is added as a carrier, not only the usable temperature range can be further widened but also the selectivity of nitrogen oxides is further improved, and the removal efficiency of nitrogen oxides is improved even by the amount of reducing agent And the present invention has been completed.

In the present invention, the exhaust gas purifying catalyst may be one which is used for removing nitrogen oxides (NOx) in the exhaust gas discharged from an internal combustion engine such as a diesel engine, an oil boiler and a gas turbine.

One aspect of the method for producing the catalyst for purification of exhaust gas of the present invention

a) heating a mixed solution of manganese salt, copper salt, base and distilled water to prepare a first mixed solution in which a gel is formed, charging the mixture into a reactor, and aging the mixture in a state of being pressurized with air;

b) adding distilled water to the reactor while reducing the pressure of the reactor to normal pressure to cool the first mixed solution, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide carrier;

c) heating a mixture of the manganese oxide-copper oxide carrier, cobalt salt, base, and distilled water to prepare a second mixed solution having a gel, adding the mixture to the reactor, and aging the mixture while pressurizing with air; And

d) cooling the second mixed solution by adding distilled water while lowering the pressure of the reactor to normal pressure, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide-cobalt oxide carrier;

.

In one embodiment of the present invention, in step a), the manganese salt and the copper salt may be used such that the molar ratio of manganese salt / copper salt is 0.2 to 3.2.

In one embodiment of the present invention, in the step c), the cobalt salt may be used so that the molar ratio of cobalt salt / manganese salt is 0.01 to 1.

In one embodiment of the present invention, the aging in steps a) and c) may be carried out while maintaining the pressure of the reactor at 2 to 100 atm.

In one embodiment of the present invention, the manganese salt is selected from the group consisting of manganese chloride (MnCl ₂ ), manganese nitrate (Mn (NO ₃ ) ₂ ), manganese sulfate (MnSO ₄ ), manganese perchlorate (Mn (ClO ₄ ) ₂ ) Or a mixture of two or more thereof.

In one embodiment of the present invention, the copper salt is at least one selected from the group consisting of copper chloride (CuCl ₂ ), copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ), copper perchlorate (Cu (ClO ₄ ) ₂ ) Or a mixture of two or more selected from the group consisting of

In one embodiment of the present invention, the cobalt salt is at least one selected from the group consisting of cobalt chloride (CoCl ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt sulfate (CoSO ₄ ) It may be a mixture.

In an embodiment of the present invention, the base may be selected from sodium carbonate, sodium hydroxide or mixtures thereof.

In one embodiment of the present invention, in any one or more of the steps selected in steps a) and c), the mixed liquid further comprises a carrier, wherein the carrier is selected from the group consisting of zeolite, alumina, silica, zirconia, titania, ceria, And may be any one or a mixture of two or more selected.

In one embodiment of the present invention, the carrier may be a zeolite calcined in advance in an inert gas atmosphere.

In one aspect of the present invention, in any one or more of the steps selected in the steps a) and c), the mixed liquid further comprises a metal additive, wherein the metal additive is selected from the group consisting of silver nitrate, chromium nitrate, zinc nitrate, lanthanum nitrate, Sodium nitrate, or a mixture of two or more thereof.

In one embodiment of the present invention, the BET surface area of the manganese oxide-copper oxide-cobalt oxide support may be 200 to 1000 m ² / g.

Hereinafter, each configuration of the present invention will be described in more detail.

The step a) of the present invention is a step of preparing a mixed solution in which a gel is formed by heating a mixture of manganese salt, copper salt, base and distilled water. The mixture solution in which the gel is formed is in a slurry state in which solid particles are dispersed.

In one embodiment of the present invention, the content of the manganese salt and the copper salt is used such that the manganese / copper molar ratio is from 0.2 to 3.2. That is, by increasing the content of manganese in comparison with copper, it is possible to further increase the nitrogen oxide removal efficiency at a low temperature region of 150 to 250 ° C. If the molar ratio of copper to the content of manganese is less than 0.2, the removal efficiency of nitrogen oxides may be insufficient. If the content of copper is larger than 3.2 to manganese content, catalytic activity may be deteriorated due to lack of manganese crystal. The removal efficiency of nitrogen oxides can be improved.

In one embodiment of the present invention, the manganese salt is selected from the group consisting of manganese chloride (MnCl ₂ ), manganese nitrate (Mn (NO ₃ ) ₂ ), manganese sulfate (MnSO ₄ ), manganese perchlorate (Mn (ClO ₄ ) ₂ ) And the like, or a mixture of two or more thereof, but is not limited thereto.

In one embodiment of the present invention, the copper salt is at least one selected from the group consisting of copper chloride (CuCl ₂ ), copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ), copper perchlorate (Cu (ClO ₄ ) ₂ ) , Or a mixture of two or more thereof.

In one embodiment of the present invention, the base used in step a) may be sodium carbonate, sodium hydroxide, or a mixture thereof. The base is added in a controlled manner in the molar ratio of the base to the sum of the molar ratios of the manganese salt and the copper salt in the mixed solution, that is, the molar ratio of the manganese salt and the copper salt / the molar ratio of the base is 1 to 10 molar ratio. If the above range is less than 1, the synthesized catalyst may weaken the role of trapping oxygen in the air, and if it exceeds 10, the oxidation reaction may be slow and the catalyst performance may be deteriorated.

In one aspect of the present invention, from the viewpoint of further improving the performance of the catalyst, if necessary, the first mixed solution of step a) further contains at least one metal component selected from silver, chromium, zinc, lanthanum and neodymium can do. In order to further include such a metal component, the first mixed solution in step a) may further contain a metal additive selected from the group consisting of silver nitrate, chromium nitrate, zinc nitrate, lanthanum nitrate, neodymium nitrate, have. The content thereof is preferably in the range of 0.01 to 10 in a molar ratio with respect to the sum of the manganese salt and the copper salt. The molar ratio of the metal additive to the total molar ratio of the manganese salt and the copper salt / metal additive is in the range of 0.01 to 10 molar ratio. If it is less than 0.01, the effect of improving the catalyst performance is insignificant. If it is more than 10, the active site of the catalyst may decrease, and the catalyst performance may be lowered.

In one embodiment of the present invention, the heating in step a) may be carried out at a temperature in the range of 60 to 100 占 폚. If the heating temperature is lower than 60 ° C, the gel formation may not be performed well. If the heating temperature exceeds 100 ° C, the stability of the reaction system is lowered due to evaporation of water or the reaction rate is excessively increased, It may be difficult to form.

In the step a), stirring may be carried out to achieve a uniform reaction. It is appropriate that the heating time of step a) is within the range of 20 minutes to 2 hours.

In one aspect of the present invention, a carrier may be included for increasing the activity of the catalyst. As the carrier, any one or a mixture of two or more selected from zeolite, alumina, silica, zirconia, titania, ceria and chromia can be used, but is not limited thereto.

The catalyst containing the carrier may be prepared by adding a carrier to the first mixed solution of step a), but the first mixed solution may be supported on the carrier by a method generally known in the art. Specifically, it is preferable that the denitrification performance is not deteriorated, and examples thereof include an ion exchange method and an impregnation-supporting method.

More specifically, it may be to use a zeolite as the carrier, more preferably from previously in a high temperature region of 250 ℃ to 300 ℃ by using a firing zeolite under an inert gas atmosphere, excellent in removal activity of nitrogen oxides and sulfur dioxide (SO ₂ The catalyst for purification of exhaust gas can be provided.

The use of MFI type zeolite or FER type zeolite is preferable because the removal efficiency of nitrogen oxides is further improved in the range of 200 to 300 ° C. and the amount of the reducing agent can be reduced, though the zeolite is not limited. Further, it has been found that the removal efficiency of nitrogen oxides and the durability against sulfur dioxide are further improved in the range of 200 to 300 ° C by firing the zeolite in an inert gas atmosphere such as nitrogen or argon in advance.

The content of the carrier is not limited, but it may be 0.1 to 10 parts by weight based on 100 parts by weight of the first mixed solution, and it is preferable that the removal efficiency of the target nitrogen oxide is excellent in the above range, Do not.

In one embodiment of the present invention, the first mixed liquid in which the gel is formed is put into a reactor and aged under pressure with air. The aging may be performed using a reaction device as shown in FIG. After injecting the first mixed solution in which the gel is formed in the reaction vessel, the reactor lid is tightened to seal the reactor and air is injected through the air inlet. It is preferable that the pressure measured by the pressure gauge is at least 2 atmospheres, more preferably at least 3 atmospheres, because the effect of pressurization may be negligible when the aging pressure is less than 2 atm. Further, although it is not necessary to limit the upper limit of the reaction pressure, if the pressure is too high, the production process may not be easy, and the specific surface area may be rather reduced. More preferably from 2 to 50 atm, and even more preferably from 3 to 10 atm. The reaction time ages the gel in the range of 1 hour to 10 hours while maintaining the above pressure. It is more preferable that the aging process is performed at a high temperature and a high pressure by maintaining the temperature of the reactor at 60 to 100 ° C. When the aging temperature is less than 60 ° C, the increase of the effect is insignificant. When the aging temperature is more than 100 ° C, the stability of the reaction system is lowered due to evaporation of water or the reaction rate is excessively increased, so that the catalytic generation of the crystalline lattice is difficult and the surface area is small.

The manganese-based oxide catalyst according to the present invention is produced by forming a relatively large number of protruding functional groups having a high crystal density and a different surface oxidation state, It is presumed that the active site is increased.

In one embodiment of the present invention, the step of cooling the mixed solution in which the gel is formed by introducing distilled water while lowering the reactor pressure to normal pressure in the step b) will be described. In this manufacturing step, the reactor is depressurized and distilled water at room temperature is added thereto in an excess amount to rapidly cool the mixed solution in which the gel is formed, thereby increasing the specific surface area of the manganese-based oxide and maintaining the generated functional groups. The amount of distilled water to be added is such that the temperature of the mixed solution can be rapidly cooled from room temperature to 40 DEG C, and it is appropriate to use distilled water at a volume ratio of 5 to 10 times the volume of the mixed solution.

Next, after the aging step, the gel is obtained by filtration, washed with distilled water and calcined in an air atmosphere to prepare a manganese oxide-copper oxide carrier. The washing is preferably carried out several times so that the content of impurities is less than 100 ppm. The firing may be performed at a temperature of 300 to 800 ° C, more specifically, 400 to 700 ° C. The catalyst having a large specific surface area can be produced within the above range, but the present invention is not limited thereto.

Further, in one embodiment of the present invention, it may further comprise removing moisture using a rotary vacuum evaporator before the firing.

Further, in one embodiment of the present invention, it may further comprise molding in the form of pellets or the like before the firing.

In one embodiment of the present invention, step c) is a step of further reacting a second mixed liquid containing a manganese oxide-copper oxide carrier and a cobalt salt. At this time, the heating and aging are the same as those described in step a), so that the explanation thereof is omitted, and the heating and aging conditions may be the same as or different from those in step a).

The second mixed solution means a mixed solution in which a gel is formed by heating a mixed solution of the manganese oxide-copper oxide carrier, cobalt salt, base, and distilled water. The mixture solution in which the gel is formed is in a slurry state in which solid particles are dispersed.

In one embodiment of the present invention, the cobalt salt is any one or two selected from the group consisting of cobalt chloride (CoCl ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt sulfate (CoSO ₄ ) Or a mixture thereof, but is not limited thereto.

In one embodiment of the present invention, the content of the cobalt salt is used such that the molar ratio of cobalt salt / manganese salt is 0.01 to 1. More preferably, the molar ratio of the cobalt salt to the sum of the manganese salt and the copper salt, that is, the sum of the cobalt salt / manganese salt and the copper salt is 0.01 to 1 mole ratio. By using it in the above range, the removal rate of nitrogen oxide is further improved, and at the same time, the nitrogen oxide removal efficiency can be improved not only in the low temperature region but also in the high temperature region up to 300 캜.

The base used in step c) may be sodium carbonate, sodium hydroxide, or a mixture thereof. The base is added by adjusting the molar ratio of the base to the molar ratio of the cobalt salt in the mixed solution, that is, the molar ratio of the cobalt salt / base is 1 to 10 molar ratio depending on the application of the catalyst. If the above range is less than 1, the synthesized catalyst may weaken the role of trapping oxygen in the air, and if it exceeds 10, the oxidation reaction may be slow and the catalyst performance may be deteriorated.

In an embodiment of the present invention, the step c) is carried out in the same manner as in step a) from the viewpoint of further improving the performance of the catalyst, if desired, from silver, chromium, zinc, lanthanum and neodymium And may further comprise at least one metal component selected. In order to further include such a metal component, the second mixed solution in step c) may further contain a metal additive selected from the group consisting of silver nitrate, chromium nitrate, zinc nitrate, lanthanum nitrate, neodymium nitrate, have. The content thereof is preferably 0.01 to 10 molar ratio with respect to the cobalt salt. The molar ratio of the cobalt salt / metal additive may be in the range of 0.01 to 10 molar ratio. If it is less than 0.01, the effect of improving the catalyst performance is insignificant. If it is more than 10, the active site of the catalyst may decrease, and the catalyst performance may be lowered.

In one embodiment of the present invention, step c) may include a carrier for increasing the activity of the catalyst as in step a). As the carrier, any one or a mixture of two or more selected from zeolite, alumina, silica, zirconia, titania, ceria and chromia can be used, but is not limited thereto.

The catalyst containing the carrier may be prepared by adding a carrier to the second mixed solution of the step c), but it is not limited thereto and the carrier may be supported with the second mixed solution by a method generally known in the art. Specifically, it is preferable that the denitrification performance is not deteriorated, and examples thereof include an ion exchange method and an impregnation-supporting method.

More specifically, it may be to use a zeolite as the carrier, more preferably from previously in a high temperature region of 250 ℃ to 300 ℃ by using a firing zeolite under an inert gas atmosphere, excellent in removal activity of nitrogen oxides and sulfur dioxide (SO ₂ The catalyst for purification of exhaust gas can be provided.

The use of MFI type zeolite or FER type zeolite is preferable because the removal efficiency of nitrogen oxides is further improved in the range of 200 to 300 ° C. and the amount of the reducing agent can be reduced, though the zeolite is not limited. Further, it has been found that the removal efficiency of nitrogen oxides and the durability against sulfur dioxide are further improved in the range of 200 to 300 ° C by firing the zeolite in an inert gas atmosphere such as nitrogen or argon in advance.

Although the content of the carrier is not limited, it may be 0.1 to 10 parts by weight based on 100 parts by weight of the second mixed solution, and is preferably within the above range because the desired removal efficiency of nitrogen oxides is excellent. Do not.

In an embodiment of the present invention, the step of cooling the mixed solution by adding distilled water while lowering the pressure of the reactor to normal pressure in step d) is the same as step b) described above, so that further explanation is omitted. The step d) may be carried out under the same or different conditions as the step b).

In the catalyst for purification of exhaust gas according to the present invention, the reducing agent is preferably a reducing power sufficient at the temperature at the time of reduction treatment of the combustion exhaust gas using ammonia.

In one embodiment of the present invention, the shape of the catalyst for purification of exhaust gas may be arbitrarily changed depending on the conditions of introduction of the reactor or exhaust gas to be applied, such as powder, granule, pellet, honeycomb, plate, It does not.

The BET surface area of the manganese oxide-copper oxide-cobalt oxide carrier prepared by the production method of the present invention may be 200 to 1000 m 2 / g, more specifically 220 to 800 m 2 / g, more preferably 240 to 600 m 2 / g. < / RTI >

Further, it is preferable that the removal efficiency of the nitrogen compound at 150 ° C is 50% or more, more specifically 50 to 80%, the removal efficiency of the nitrogen compound at 210 to 300 ° C is 90% or more, more specifically 90 to 99.9% A catalyst for purification of gas can be provided.

Hereinafter, the present invention will be described in more detail based on examples and comparative examples. However, the following examples and comparative examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the following examples and comparative examples.

1. Measurement of specific surface area (BET)

The amount of nitrogen adsorption and desorption was measured using a specific surface area meter (Micromeritics, ASAP 2420, USA) under a vacuum of 200 ° C. The adsorption desorption curve was obtained and the specific surface area was calculated by the Bruneure-Emmett-Teller (BET) method.

2. Removal efficiency of nitrogen oxide

A CLD-60 analyzer from Eco Physics Inc. was used.

The experimental setup consisted mainly of gas injection part, reactor part, and reaction gas analysis part. The flow rate of the gas supplied to the reactor was controlled using MFC (Mass Flow Controller, SM-TEK Co.) from each cylinder of NO, N ₂ , O ₂ and NH ₃ . Further, were the supply of moisture is N ₂ is to be injected into the reactor by the water-containing through a bubbler, this time was kept constant the bubbler inner temperature to 60 ℃ using an electric furnace in the bubbler external to a constant amount of feed. The gas supply pipe is made of a stainless steel pipe as a whole, and the formation of salts such as NH ₄ NO ₃ and NH ₄ NO _{2 which} are caused by the reaction of NO and NH ₃ is prevented and the heating band is wound around the reaction gas at 180 ° C. . The reactor was a continuous flow type fixed bed reactor with a stainless steel (SUS 316) reactor having an inner diameter of 20 mm and a height of 30 mm and a quartz wool was used to fix the catalyst layer. The temperature of the reactor was controlled by a PID temperature controller using a k-type thermocouple mounted outside the reactor. A k-type thermocouple was also installed at the top of the catalyst bed to measure the temperature of the gas inlet. All the gases were analyzed by introducing water after removing moisture from the gas using a water trap in the chiller before entering the analyzer. At this time, the temperature of the reactor was changed from 60 to 300 ° C., the concentration of NO supplied was controlled to 300 to 500 ppm, and the concentration of NH ₃ was controlled to 300 to 500 ppm. The oxygen concentration was maintained at 3 to 5% and the space velocity was made to be in the range of 10,000 to 40,000 hr ^-1 .

[Example 1]

Manganese chloride hydrate _{(MnCl 2 · H 2 O)} 396g (2.75 mol) of copper chloride hydrate _{(CuCl 2 · H 2 O)} 136g (0.89 mol) and sodium carbonate (Na ₂ CO _{3) 2} L distilled water to 252g (2.38 mol) And stirred for 30 minutes while maintaining the temperature at 90 캜.

The first mixed solution having a gel formed by heating was introduced into a stainless steel reactor as shown in FIG. 1, and air was injected thereinto to maintain the atmosphere at 5 atm for aging for 4 hours. 10 liters of distilled water at room temperature was added to remove the pressure, and the temperature was immediately dropped. The reaction product was sufficiently washed with a large amount of distilled water until the amount of unnecessary carbon and other impurities became 100 ppm or less. Molded into pellets having a diameter of 1.0 mm, and then heated at 500 DEG C for 5 hours in an air atmosphere to be fired.

190 g (0.8 mol) of cobalt chloride hydrate (CoCl ₂揃 6H ₂ O) and 136 g (0.89 mol) of copper chloride hydrate (CuCl ₂揃 H ₂ O) were dissolved in 1 liter of distilled water and then 500 g of the manganese oxide- And the mixture was stirred for 30 minutes while maintaining the temperature at 90 ° C.

The second mixed solution in which the gel was formed by heating was introduced into a stainless steel reactor as shown in FIG. 1, and air was injected thereinto to maintain the atmosphere at 5 atm for aging for 4 hours. 10 liters of distilled water at room temperature was added to remove the pressure, and the temperature was immediately dropped. The reaction product was sufficiently washed with a large amount of distilled water until the amount of unnecessary carbon and other impurities became 100 ppm or less. Molded into pellets having a diameter of 1.5 mm, and then heated at 500 DEG C for 5 hours under an air atmosphere to be fired.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 240 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

Observation of the surface and morphology of the prepared catalyst (manganese oxide-copper oxide-cobalt oxide carrier) with an electron microscope (SEM, scanning electron microscope) showed that spherical and acicular shapes were evenly distributed .

[Example 2]

Except that an MFI (ZSM-5) type zeolite (HSZ-830NHA, manufactured by Nippon Dojo Co., Ltd.) was added to the first mixed solution of Example 1 and the step of immersing and stirring the mixture at 70 캜 for 12 hours to carry out ion exchange Was prepared in the same manner as in Example 1.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 245 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

Observation of the surface and morphology of the prepared catalyst (manganese oxide-copper oxide-cobalt oxide carrier) with an electron microscope (SEM, scanning electron microscope) showed that spherical and acicular shapes were evenly distributed .

[Example 3]

The procedure of Example 2 was repeated except that MFI (ZSM-5) type zeolite calcined at 600 占 폚 for 15 hours in a nitrogen atmosphere was used.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 250 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

Observation of the surface and morphology of the prepared catalyst (manganese oxide-copper oxide-cobalt oxide carrier) with an electron microscope (SEM, scanning electron microscope) showed that spherical and acicular shapes were evenly distributed .

[Example 4]

Except that 170 g (0.7 mol) of cobalt chloride hydrate (CoCl ₂ .6H ₂ O) was used in the above Example 1.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 242 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

Observation of the surface and morphology of the prepared catalyst (manganese oxide-copper oxide-cobalt oxide carrier) with an electron microscope (SEM, scanning electron microscope) showed that spherical and acicular shapes were evenly distributed .

[Comparative Example 1]

Manganese chloride hydrate _{(MnCl 2 · H 2 O)} 396g (2.75 mol) of copper chloride hydrate _{(CuCl 2 · H 2 O)} 136g (0.89 mole) of cobalt chloride hydrate _{(CoCl 2 · 6H 2 O)} 190g (0.8 mol) And 252 g (2.38 mol) of sodium carbonate (Na ₂ CO ₃ ) were dissolved in 3 liters of distilled water and stirred for 30 minutes while maintaining the temperature at 90 ° C. As shown in FIG. 1, the mixed solution, in which the gel was formed by heating, was charged into a stainless steel reactor, and air was injected thereinto to maintain the pressure of 5 atm for aging for 4 hours. 10 liters of distilled water at room temperature was added to remove the pressure, and the temperature was immediately dropped. The reaction product was sufficiently washed with a large amount of distilled water until the amount of unnecessary carbon and other impurities became 100 ppm or less. Molded into pellets having a diameter of 1.5 mm, and then heated at 500 DEG C for 5 hours under an air atmosphere to be fired.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 220 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

[Comparative Example 2]

The aging step was carried out in the same manner as in Example 1 except that the step of aging was conducted at room temperature and atmospheric pressure for 4 hours.

The specific surface area of the prepared manganese oxide-copper oxide-cobalt oxide support was 180 m 2 / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

[Comparative Example 3]

Manganese chloride hydrate was used alone, and cobalt chloride hydrate and copper chloride hydrate were not used.

The specific surface area of the prepared catalyst was 150 m < 2 > / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

[Comparative Example 4]

Cobalt chloride hydrate was used alone, and manganese chloride hydrate and copper chloride hydrate were not used.

The specific surface area of the prepared catalyst was 145 m < 2 > / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

[Comparative Example 5]

Copper chloride hydrate was used alone, and manganese chloride hydrate and cobalt chloride hydrate were not used.

The specific surface area of the prepared catalyst was 148 m < 2 > / g, and the removal efficiency of nitrogen oxide was measured and shown in Tables 1 and 2 below.

The following Table 1 shows the catalysts prepared in Examples 1 to 4 and Comparative Examples 1 to 5 in which NO: 400 ppm, NO / NH ₃ : 1 molar ratio, O ₂ concentration: 3%, space velocity: 20,000 hr ^-1 (NOx) removal efficiency by varying the temperature in the exhaust gas.

NOx removal efficiency (%) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 150 ℃ 55 58 60 40 30 10 15 12 6 170 ℃ 72 86 88 58 62 22 30 21 10 190 ℃ 85 92 95 82 78 36 45 45 13 210 ℃ 92 98 99 90 88 45 50 68 48 230 ℃ 96 98 99 92 90 68 78 70 75 250 ℃ 96 98 99 95 90 89 88 82 86 270 ℃ 97 98 99 95 88 80 70 60 86 290 ° C 97 98 99 95 75 50 50 45 65 310 ° C 97 98 99 95 40 26 26 30 48

As shown in Table 1, it can be seen that the catalyst prepared in the example of the present invention is excellent in the removal efficiency of nitrogen oxides at 150 to 310 ° C, and that the removal efficiency is excellent even in the low temperature region as compared with the comparative example.

As shown in Comparative Example 1, when the copper chloride chloride, manganese chloride hydrate and cobalt chloride hydrate were simultaneously added, the removal efficiency of the nitrogen oxides was lowered compared with the examples, and the removal efficiency was lowered at a temperature higher than 300 ° C Respectively.

In addition, as shown in Comparative Examples 2 to 5, it was confirmed that the removal efficiency of nitrogen oxides was lowered when the metal salts were not used or the aging process was used alone.

The following Table 2 shows the results of measurement of NO: 400 ppm, NO / NH ₃ : 1 molar ratio, O ₂ concentration: 3%, space velocity: 20,000 hr ^-1 (NOx) removal efficiency while injecting 50 ppm of SO ₂ .

NOx removal efficiency (%) Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 150 ℃ 54 56 62 40 28 10 8 5 5 170 ℃ 72 85 90 58 60 15 12 10 8 190 ℃ 85 90 96 83 75 25 40 15 10 210 ℃ 93 96 99 90 80 38 45 40 42 230 ℃ 95 98 99 91 88 56 72 68 70 250 ℃ 96 98 99 95 88 70 80 75 80 270 ℃ 97 98 99 95 86 60 65 60 75 290 ° C 97 98 99 95 70 58 48 40 53 310 ° C 97 98 99 95 35 23 22 26 38

As shown in Table 2, it can be seen that the catalyst prepared in the example of the present invention is still excellent in the removal efficiency of nitrogen oxide even when sulfur dioxide is added, and thus it is excellent in resistance to sulfur dioxide.

In Comparative Examples 1 to 5, it was confirmed that the removal efficiency of nitrogen oxides (NOx) was lowered in comparison with those in Table 1 by the introduction of sulfur dioxide.

Claims (12)

a) heating a mixed solution of manganese salt, copper salt, base and distilled water to prepare a first mixed solution in which a gel is formed, charging the mixture into a reactor, and aging the mixture in a state of being pressurized with air;
b) adding distilled water to the reactor while reducing the pressure of the reactor to normal pressure to cool the first mixed solution, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide carrier;
c) heating a mixture of the manganese oxide-copper oxide carrier, cobalt salt, base, and distilled water to prepare a second mixed solution having a gel, adding the mixture to the reactor, and aging the mixture while pressurizing with air; And
d) cooling the second mixed solution by adding distilled water while lowering the pressure of the reactor to normal pressure, and then washing the resultant gel and firing in an air atmosphere to prepare a manganese oxide-copper oxide-cobalt oxide carrier;
Wherein the exhaust gas purifying catalyst is a catalyst for purifying exhaust gas. The method according to claim 1,
Wherein in step (a), the manganese salt and the copper salt are used so that the molar ratio of manganese salt / copper salt is 0.2 to 3.2. The method according to claim 1,
Wherein the cobalt salt is used so that the mole ratio of cobalt salt / manganese salt is 0.01 to 1 in step c). The method according to claim 1,
Wherein the aging in the steps a) and c) is carried out while maintaining the pressure of the reactor at 2 to 100 atm. The method according to claim 1,
Wherein the manganese salt is selected from the group consisting of manganese chloride (MnCl ₂ ), manganese nitrate (Mn (NO ₃ ) ₂ ), manganese sulfate (MnSO ₄ ), manganese perchlorate (Mn (ClO ₄ ) ₂ ) Wherein the catalyst is one or a mixture of two or more thereof. The method according to claim 1,
Wherein the copper salt is selected from the group consisting of copper chloride (CuCl ₂ ), copper nitrate (Cu (NO ₃ ) ₂ ), copper sulfate (CuSO ₄ ), copper perchlorate (Cu (ClO ₄ ) ₂ ) Or a mixture of two or more thereof. The method according to claim 1,
Wherein the cobalt salt is any one or a mixture of two or more selected from the group consisting of cobalt chloride (CoCl ₂ ), cobalt nitrate (Co (NO ₃ ) ₂ ), cobalt sulfate (CoSO ₄ ) Gt; The method according to claim 1,
Wherein the base is selected from sodium carbonate, sodium hydroxide or a mixture thereof. The method according to claim 1,
In any one or more of the steps selected in the steps a) and c), the mixed liquid further comprises a carrier,
Wherein the carrier is any one or a mixture of two or more selected from zeolite, alumina, silica, zirconia, titania, ceria and chromia. 10. The method of claim 9,
Wherein the carrier is a zeolite calcined in advance in an inert gas atmosphere. The method according to claim 1,
In any one or more of the steps selected in steps a) and c), the mixed liquid further comprises a metal additive,
Wherein the metal additive is any one or a mixture of two or more selected from silver nitrate, chromium nitrate, zinc nitrate, lanthanum nitrate and neodymium nitrate. The method according to claim 1,
And the BET surface area of the manganese oxide-copper oxide-cobalt oxide carrier is 200 to 1000 m ² / g.

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