KR20190068173A - SCR Catalyst Added Carbon Supported Active Catalytic Materials and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to a denitration catalyst for selective catalytic reduction reaction in which a catalytically active substance is supported on a carbon material and a manufacturing method thereof. More particularly, the present invention relates to: the denitration catalyst for selective catalytic reduction reaction in which the catalytically active substance is supported on the carbon material which has excellent removal efficiency of nitrogen oxides in exhaust gas despite a small supported amount of vanadium and tungsten, does not cause secondary environmental pollution, and has excellent wear resistance and strength so that removal efficiency of nitrogen oxides is not reduced even during long-term operation, and at the same time, it is easily to manufacture, thereby being able to contribute to commercialization; the manufacturing method thereof.

Description

TECHNICAL FIELD [0001] The present invention relates to an NO x removal catalyst for a selective catalytic reduction reaction in which a catalytic active material is supported on a carbon material,

The present invention relates to a denitration catalyst for selective catalytic reduction reaction in which a catalytic active material is supported on a carbon material and a method for preparing the same. More particularly, the present invention relates to a denitration catalyst for removing NOx, To a NO x removal catalyst for a selective catalytic reduction reaction in which a catalytic active material is supported on a carbon material, and a production method thereof.

Nitrogen oxides (NO _X ) in exhaust gas from fixed sources such as chemical plants, power plants, boilers, and incinerators, and from sources such as automobiles and ships, contain sulfur oxides (SO _x ), dusts, dioxins, heavy metals and volatile organic compounds Volatile Organic Compounds) are well known as substances causing environmental pollution.

NOx is mainly produced by the reaction of nitrogen and oxygen in the presence of excess air in the combustion equipment of a high temperature, the nitrogen monoxide (NO), nitrogen dioxide (NO _2), dinitrogen oxide (N ₂ O), diantimony nitrogen (N ₂ O ₃ ), Nitrous oxide (N ₂ O ₄ ), and dinitrogen monoxide (N ₂ O ₅ ). Of these, nitrogen monoxide is a very harmful carcinogenic substance and causes serious air pollution. It is a pollution source that causes acid rain and smog generation and destroys the global environment. Therefore, in order to suppress the occurrence of this phenomenon, it is necessary to develop technologies to suppress the occurrence of combustion conditions such as hypoxic combustion and exhaust gas circulation, Efforts are underway.

However, unlike other air pollutants, nitrogen oxides are inevitably generated in a high temperature combustion process, and since they are highly stable compounds, improvements in combustion technology can not sufficiently remove nitrogen oxides. Therefore, Has attracted attention.

This post-treatment technique can be roughly classified into a wet process and a dry process depending on whether an aqueous solution is used. Among them, a selective catalytic reduction (SCR) process which is superior in terms of removal efficiency and economical efficiency as a dry process is widely used commercially.

In the selective catalytic reduction process, a reducing agent such as NH ₃ , urea, hydrocarbon and the like is used for removing NO _x , and the reducing agent is used to reduce NO _x to a harmless gas such as N ₂ or H ₂ O on the catalyst. In the case of using ammonia in the reducing agent, in addition to the odor and toxicity of ammonia, the ammonium sulfate produced by reacting unreacted ammonia in the exhaust gas with the SO ₃ in the exhaust gas as a result of oxidation of SO ₂ in the exhaust gas, Is a major cause to shorten the time. Therefore, the conversion of SO _x should be considered when preparing the catalyst.

Recently, V ₂ O ₅ -WO ₃ -TiO ₂ catalyst, which is widely used and widely used, is the most widely used catalyst for NO _x treatment in exhaust gas of power plants and incinerators because of its high reactivity and strong field adaptability . Among these catalysts, V ₂ O ₅ and WO ₃ catalyzes the conversion of NO _x to N ₂ by the redox cycle, thereby increasing the activity of the catalyst. However, when excess amount is added, the reaction of oxidizing NH ₃ to N ₂ O occurs in the high temperature region , The SOx conversion rate is high, and when it is released into the environment as heavy metals, it greatly affects the human body and the environment. Therefore, V ₂ O ₅ The content of WO ₃ is limited. Recently, demand and prices have increased and V ₂ O ₅ WO ₃ prices are reported to be increasing rapidly. Therefore, it is required to reduce the use amount of vanadium and tungsten.

Korean Patent No. 1434936 discloses a process for producing a cerium-zirconium mixed oxide by impregnating a homogeneous cerium-zirconium mixed oxide with an aqueous solution of chromium, molybdenum, tungsten or a mixture thereof to form a cerium- However, since the vanadium-free catalyst is free from vanadium, it is harmless to the environment and has an advantage of excellent aging stability under hydrothermal conditions. However, since it is required to operate at a high temperature, the operation cost is high, and in the presence of excess oxygen There is a problem that the inactivating phenomenon is caused by the low specific surface area.

Korean Patent No. 1565982 discloses a SCR catalyst in which titanium dioxide and tungsten oxide are mixed with a vanadium support in which a small amount of vanadium is dispersed and supported on graphene in order to reduce the amount of vanadium, The substance supported on the graphene support is limited to vanadium, and the amount of tungsten that is expensive as well as vanadium is maintained. Further, by adding a process of treating the vanadium-loaded materials with titanium dioxide, There is a problem that efficiency is low.

Korean Registered Patent No. 1434936 (Published on Jul. 29, 2009) Korean Registered Patent No. 1565982 (Disclosure Date: 2015.08.26)

The main object of the present invention is to solve the above-mentioned problems, and it is an object of the present invention to provide an exhaust gas purifying apparatus which is excellent in nitrogen oxide removal efficiency in exhaust gas despite small amount of vanadium and tungsten to be loaded, An NO x removal catalyst for a selective catalytic reduction reaction in which a catalytic active material is supported on a carbon material, which is excellent in strength and does not deteriorate the NO x removal efficiency even during long-term operation, and can be easily produced and contributes to commercialization .

According to an aspect of the present invention, there is provided a method for preparing a metal precursor solution, comprising the steps of: (a) preparing an aqueous metal precursor solution by mixing a vanadium precursor aqueous solution, a tungsten precursor aqueous solution, and a titanium precursor aqueous solution; (b) impregnating the metal precursor aqueous solution with graphene oxide or reduced graphene oxide to obtain an impregnated product; And (c) drying the impregnated material and then calcining the impregnated material.

In one preferred embodiment of the present invention, the aqueous metal precursor solution of step (a) comprises 0.1 to 3 parts by weight of the vanadium precursor and 1 to 10 parts by weight of the tungsten precursor, based on 100 parts by weight of the titanium precursor. .

In one preferred embodiment of the present invention, the content of graphene oxide or reduced graphene oxide in the step (b) is 5 parts by weight to 15 parts by weight with respect to 100 parts by weight of the titanium precursor.

Another embodiment of the present invention provides an NO x removal catalyst for selective catalytic reduction characterized in that catalytically active vanadium oxide, tungsten oxide and titanium oxide are supported on graphene oxide or reduced graphene oxide as a catalyst support .

In another preferred embodiment of the present invention, the denitration catalyst for the selective catalytic reduction reaction comprises 0.1 to 3 parts by weight of vanadium oxide and 1.0 to 10 parts by weight of tungsten oxide per 100 parts by weight of titanium oxide can do.

In another preferred embodiment of the present invention, the denitration catalyst for the selective catalytic reduction reaction may include 5 to 15 parts by weight of graphene oxide or reduced graphene oxide per 100 parts by weight of the titanium oxide.

The NO x removal catalyst for selective catalytic reduction according to the present invention is excellent in the removal efficiency of nitrogen oxides in the exhaust gas despite the reduction of vanadium and tungsten carried on the catalyst support and the treated gas does not cause secondary environmental pollution, And strength, so that the nitrogen oxide removal efficiency is not lowered even in a long-term operation, and the production is easy and contributes to commercialization.

1 is a process diagram of a method for preparing a NO x removal catalyst for selective catalytic reduction according to the present invention.
2 is a graph showing the removal efficiency of nitrogen oxide according to the reaction temperature.
3 is a TEM image of an NO x removal catalyst for selective catalytic reduction reaction, wherein (a) is a TEM image of an NO x removal catalyst prepared in Example 1, (b) is a TEM image of a NO x reduction catalyst prepared in Comparative Example 1 TEM image of the denitration catalyst.
FIG. 4 is a graph showing ammonia temperature desorption (NH ₃ -TPD) measured with respect to the temperature of the NO x removal catalyst prepared in Example 1 and Comparative Example 1.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The terms "about "," substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

As used herein, the term "graphene" refers to a polycyclic aromatic molecule formed by covalent bonding of a plurality of carbon atoms, wherein the carbon atoms linked by the covalent bond form a 6-membered ring as the basic repeating unit, It is also possible to further include a toric ring and / or a 7-membered ring. The graphene thus appears as a single layer of covalently bonded carbon atoms (usually sp2 bonds). The graphene may have various structures, and such a structure may vary depending on the content of the 5-membered ring and / or the 7-membered ring which may be contained in the graphene.

In one aspect, the present invention provides a method for preparing a metal precursor solution, comprising: (a) preparing a metal precursor aqueous solution by mixing a vanadium precursor aqueous solution, a tungsten precursor aqueous solution, and a titanium precursor aqueous solution; (b) impregnating the metal precursor aqueous solution with graphene oxide or reduced graphene oxide to obtain an impregnated product; And (c) drying the impregnated material and then calcining the impregnated material.

More specifically, in the method for preparing a NO x removal catalyst for selective catalytic reduction according to the present invention, graphene is used as a catalyst support to reduce the amount of raw materials of vanadium and tungsten which are expensive and cause environmental problems. , It is possible to produce a denitration catalyst for selective catalytic reduction reaction which is excellent in nitrogen oxide removal efficiency in the exhaust gas and does not deteriorate the nitrogen oxide removal efficiency even in long-term operation by uniformly dispersing the catalytically active substance in the graphene catalyst support have.

Hereinafter, the present invention will be described in more detail with reference to the drawings. 1 is a process diagram of a method for preparing a NO x removal catalyst for selective catalytic reduction according to the present invention.

The step (a) according to the present invention is a step of preparing an aqueous metal precursor solution by mixing a vanadium precursor aqueous solution, a tungsten precursor aqueous solution and a titanium precursor aqueous solution.

The metal precursor aqueous solution is obtained by mixing a vanadium precursor aqueous solution, a tungsten precursor aqueous solution and a titanium precursor aqueous solution in which a vanadium precursor, a tungsten precursor and a titanium precursor are respectively dissolved in demineralized water. In this case, the amount of demineralized water can be used without limitation as long as the amount of each precursor can be sufficiently dissolved. Preferably, 5 to 10 parts by weight of each precursor may be dissolved in 100 parts by weight of demineralized water.

The vanadium precursor is used for the production of a catalytically active substance. The vanadium precursor can be used without limitation as long as it is a compound commonly used in the field of selective catalytic reduction catalysts. Preferred examples thereof include ammonium metavanadate (NH ₄ VO ₃ ) Vanadium oxytrichloride (VOCl ₃ ), vanadium oxide (V ₂ O ₅ ) and the like can be used, and ammonium metavanadate (NH ₄ VO ₃ ) is more preferable. The ammonium metavanadate (NH ₄ VO ₃ ) is environmentally friendly compared to other types of catalysts. When pyrolyzed, vanadium pentoxide (V ₂ O ₅ ) is formed. Vanadium pentoxide not only catalyzes the reduction of nitrogen oxides in the exhaust gas, (SO ₂ ) to sulfur trioxide (SO ₃ ) while sulfur trioxide (SO ₃ ) is converted into sulfuric acid (H ₂ SO ₄ ) by combining sulfur trioxide with water vapor in the exhaust gas. There is also an effect to remove.

When ammonium metavanadate is used as the vanadium precursor, it is preferable to add oxalic acid to the aqueous solution of ammonium metavanadate by slightly stirring to increase the solubility of ammonium metavanadate because the solubility of ammonium metavanadate is very small.

The vanadium precursor may be contained in an amount of 0.1 to 3 parts by weight, preferably 0.5 to 2 parts by weight, more preferably 0.6 to 2 parts by weight, based on 100 parts by weight of the titanium precursor. If the content of the vanadium precursor is less than 0.1 parts by weight, the nitrogen oxide removal effect may be insufficient. If the vanadium precursor content is more than 3 parts by weight, aggregation of the powder may occur due to a high content, It is not preferable in terms of surface and environment.

The tungsten precursor is used for the production of a catalytically active substance. The tungsten precursor can be used without limitation as long as it is a compound commonly used in the field of selective catalytic reduction catalysts, and preferably ammonium metatungstate [(NH ₄ ) ₆ W ₁₂ O ₃₉ XH ₂ O], ammonium paratungstate [(NH ₄ ) ₁₀ W ₁₂ O ₄₁ ], ammonium tungstate (H ₈ N ₂ O ₄ W), ammonium sulfur tungstate (H ₈ N ₂ S ₄ W), tungsten oxide (WO ₃ ), or the like can be used.

The content of the tungsten precursor may be 1 part by weight to 10 parts by weight, preferably 2 parts by weight to 10 parts by weight, more preferably 2 parts by weight to 8 parts by weight, based on 100 parts by weight of the titanium precursor. If the content of the tungsten precursor is less than 1 part by weight, structural stability of titanium oxide or temperature at a wide temperature range, especially at high temperature, may be insufficient. If it exceeds 10 parts by weight, And the efficiency relative to an increase in the content may not be satisfactory, which is not desirable from the viewpoints of economy and environment.

The vanadium of the vanadium precursor and tungsten of the tungsten precursor are transition metals, and the number of electrons occupying the electron orbital inside is incomplete, so that the electrons are easily lost and become a cationic state, thereby forming a compound with a titanium precursor, It improves impact resistance, heat resistance and corrosion resistance along with activation of catalytic reduction reaction. It is also not oxidized well and is stable against alkali, sulfuric acid, hydrochloric acid etc. because it easily reacts with oxygen to form oxide passivation protection film.

The titanium precursor may be titanium dioxide (TiO ₂ ), amorphous titanic acid or the like. These titanium precursors act as a support for vanadium and tungsten used as a main catalyst and a cocatalyst due to their high specific surface area, The strength is increased, the heat resistance is improved, and the lifetime of the catalyst is increased.

Next, in the step (b) according to the present invention, the aqueous metal precursor solution is impregnated with graphene oxide or reduced graphene oxide to obtain an impregnated product.

The graphene oxide (GO) is generally produced by the oxidation of graphite crystals and pulverization using ultrasonic treatment, and the reduced graphene oxide (RGO) is produced by hydrazine graphene oxide, Or the like. However, commercially available graphene oxide and reduced graphene oxide may be purchased and used.

The graphene oxide or the reduced graphene oxide may be mixed with an aqueous solution of the metal precursor or impregnated with the aqueous solution of the metal precursor by dissolving the graphene oxide or the reduced graphene oxide in the demineralized water or the aqueous solution of the graphene oxide or the reduced graphene oxide Mixed and impregnated. The amount of the desalted water may be any amount as long as the amount of the graphene oxide or the reduced graphene oxide is sufficiently dissolved. Preferably, the amount of the desalted water is 1 part by weight or less of graphene oxide or reduced graphene oxide per 100 parts by weight of the desalted water, 3 parts by weight may be added and dissolved.

The graphene oxide or the reduced graphene oxide may be contained in an amount of 5 parts by weight to 15 parts by weight, preferably 7 parts by weight to 12 parts by weight, based on 100 parts by weight of the titanium precursor. If the content of the graphene oxide or the reduced graphene oxide is less than 5 parts by weight, the particles may not uniformly disperse uniformly on the surface of the graphene due to a high content of the active material, There is a problem that the amount of the catalytically active substance supported on the graphene oxide or the reduced graphene oxide is insufficient and thus it can not sufficiently serve as a support for the catalytically active substance.

The graphene oxide or the reduced graphene oxide is impregnated with the above-described metal precursor aqueous solution under agitation so that the metal of the metal precursors is supported on the graphene. The impregnation may be performed at 30 ° C to 70 ° C for 1 hour to 15 hours. If the impregnation is carried out at 30 ° C or less for 1 hour or less, the impregnation may not be performed sufficiently and the yield may be lowered. If the impregnation is carried out at 70 ° C or for more than 15 hours, Which may lead to catalyst deactivation.

Thereafter, in the step (c) according to the present invention, the impregnated material is dried and then fired to produce a denitration catalyst for selective catalytic reduction.

After the impregnation step, the moisture of the obtained impregnated material is removed by using a rotary vacuum evaporator or the like, and the residual moisture contained in the micropores in the impregnated material is sufficiently dried by a dryer or the like.

If the drying temperature is too low or the drying time is too short, it may not be completely dried and may contain moisture in the catalyst micropores, which may result in degradation of the activity. If the drying temperature is too high or the drying time is too long, The activity of the catalyst may be lowered due to the grain growth of vanadium as the main catalyst material due to the development, and the impregnation may be performed at 40 ° C to 50 ° C.

The dried product after the drying is subjected to a calcination process to control the size and the degree of dispersion of the active ingredient through heat treatment to produce a denitration catalyst for selective catalytic reduction reaction. The firing may be carried out at 400 ° C to 800 ° C for 1 hour to 3 hours, preferably in an inert atmosphere, considering the selective catalytic reduction capability of the catalyst. If the inert atmosphere can not be maintained during the firing, the graphene, which is the catalyst support material, is oxidized to cause defects of the catalyst such as vacancy and the like, May occur. In order to maintain the inert atmosphere, nitrogen, argon, helium, etc. may be injected and contained during the firing process.

In addition, when the calcination condition is less than 400 ° C or less than 1 hour, the precursor is not properly removed and the removal efficiency of the NO x removal catalyst may be reduced due to non-uniform distribution of NO x removal catalyst particles and pores , 800 ° C. or 3 hours, the durability may be lowered or the removal efficiency of nitrogen oxides may be lowered due to changes in physical properties of the catalyst active material and the material used as the catalyst support.

The firing process may be performed in various types of furnaces, such as a tube type, a convection type, and a grate type, and is not particularly limited.

The NO x removal catalyst for selective catalytic reduction reaction as described above contains vanadium, tungsten, and titanium, which are catalytically active materials, on graphene oxide or reduced graphene oxide, which is a catalyst support material, so that nitrogen oxides contained in the exhaust gas in the SCR process It is possible to stably maintain the removing activity.

In another aspect, the present invention relates to a NO x removal catalyst for selective catalytic reduction, characterized in that catalytically active vanadium oxide, tungsten oxide and titanium oxide are supported on graphene oxide or reduced graphene oxide as a catalyst support.

The NO x removal catalyst for selective catalytic reduction according to the present invention contains 5 to 15 parts by weight of graphene oxide or reduced graphene oxide per 100 parts by weight of titanium oxide. If the content of the graphene oxide or the reduced graphene oxide is out of the above range, the amount of the catalytically active material to be loaded is insufficient and the catalytically active material can not be properly performed. Alternatively, It is not uniformly dispersed evenly, and coagulation phenomenon occurs. This leads to an increase in oxidizing power due to an excessive amount of active material, thereby oxidizing ammonia, which is a reducing agent, resulting in deterioration of nitrogen oxide removal performance and oxidation of SO ₂ to SO ₃ , ₄ HSO ₄ ).

The denitration catalyst for the selective catalytic reduction reaction contains 0.1 to 3 parts by weight of vanadium oxide and 1.0 to 10 parts by weight of tungsten oxide per 100 parts by weight of titanium oxide. The denitration catalyst for the selective catalytic reduction reaction of the composition ratio is excellent in the removal efficiency of nitrogen oxide in the exhaust gas despite the small amount of vanadium and tungsten supported thereon and the processed gas does not cause secondary environmental pollution and has excellent abrasion resistance and strength So that it is possible to suppress the reduction of the catalyst activity and the life span due to the high temperature operation.

The NO x removal catalyst for selective catalytic reduction according to the present invention can be used as a coating on a structure such as a metal plate, a metal fiber, a ceramic filter, a honeycomb, an air purifier, an interior decoration, an interior / exterior material, a wallpaper, Or monolith, or may be prepared in various forms such as slate, plate, and pellet.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

< Example  1>

A vanadium precursor aqueous solution, a tungsten precursor aqueous solution and a titanium precursor aqueous solution were prepared by mixing 0.1 g of ammonium metavanadate (AMV), 0.6 g of ammonium metatungstate (AMT) and 10.0 g of titanium dioxide in 200 g of distilled water, To obtain an aqueous metal precursor solution. Then 1.0 g of reduced graphene oxide (RGO) was dispersed in 100 g of distilled water, and then the aqueous solution of the metal precursor was impregnated with the aqueous solution of the reduced precursor oxide by stirring at 60 ° C for 7 hours. After the completion of the impregnation, the impregnated material obtained was dried in an oven at 60 ° C. by removing the moisture from the impregnated material by using a rotary evaporation apparatus, and then calcined at 500 ° C. for 2 hours in a nitrogen atmosphere to obtain a denitration catalyst for selective catalytic reduction .

< Example  2 to 4 and Comparative Example  1>

The content conditions for Examples 2 to 4 and Comparative Example 1 are shown in Table 1, and a denitration catalyst for the selective catalytic reduction reaction was prepared in the same manner as in Example 1 except for the respective conditions.

division Distilled water content
(g) AMV content
(g) AMT content
(g) Titanium dioxide
Content (g) Reduced graphene oxide content (g) Example 1 700.00 0.10 0.60 10.00 1.00 Example 2 700.00 0.05 0.60 10.00 1.00 Example 3 700.00 0.10 0.30 10.00 1.00 Example 4 700.00 0.05 0.30 10.00 1.00 Comparative Example 1 200.00 0.10 0.60 10.00 -

[ Experimental Example  1]: for selective catalytic reduction reaction Of the denitration catalyst  Component measurement

The components of the NO x removal catalysts prepared in Examples 1 to 4 and Comparative Example 1 were measured through X-ray fluorescence (X-ray fluorescence, Zetium, PAN'alytical)

division
Catalyst active material (wt%) TiO ₂ WO ₃ V ₂ O ₅ Other Example 1 93.741 5.092 1.018 0.149 Example 2 94.518 4.922 0.499 0.061 Example 3 96.221 2.608 0.983 0.188 Example 4 96.657 2.665 0.491 0.187 Comparative Example 1 93.697 5.228 1.019 0.056

As shown in Table 2, it was confirmed that the results of analysis corresponding to the different added contents in the synthesis were obtained. The other material is Al ₂ O ₃ , SiO _2, etc., and is considered to be a residue existing in the material or measurement equipment used as the precursor.

[ Experimental Example  2]: for selective catalytic reduction reaction Of the denitration catalyst Denitrification performance  Measure

The NOx conversion test system consists of a catalytic reactor where the catalyst is loaded and reacted, a heater that controls the temperature of the catalytic reactor, a preheater that preheats the feed gas, a temperature control panel that controls the amount of the temperature and the feed gas, Flow Controller, and Water Pump. The temperature of the reactor was controlled in the range of 250 ° C to 500 ° C, and 0.3g of the powder type obtained in the Examples and Comparative Examples was prepared as the catalyst to be analyzed. Since 2005, the gas velocity (SV) of 60,000 ml g _cat ^-1 h ^{- 1} calculated by the criteria for the performance evaluation of NO x removal catalysts in Europe, Japan and the United States was calculated, and the total amount of gas supplied to the reactor was 300 sccm Respectively. NO gas (1% mol / mol) was flowed quantitatively at 300 ppm (v / v) and NH ₃ gas was flowed at 360 ppm (v / v). The concentration of O ₂ (1% mol / mol) was maintained at 5% (v / v) and N ₂ (high purity liquid nitrogen). In order to carry out the precise activation experiment, the reaction was performed after stabilization for a certain period of time under the corresponding reaction conditions. The analysis of the reaction gas excluding O ₂ was performed using a CLD analyzer (Chemi-luminescence detector, T200H, Teledyne) And O ₂ gas was analyzed using an O ₂ analyzer (OXITEC-5000, ENOTEC). The NOx removal efficiency was calculated by the following equation after measuring the NOx concentration change of the gas outlet passed through the gas inlet and the catalytic reaction part through the above analyzer, and is shown in FIG.

[expression]

NO _x conversion (%) = 100 × ((inlet-outlet NO _x concentration) / inlet NO _x concentration)

As shown in FIG. 2, the catalysts of Examples 1 to 3 showed better denitrification performance than the catalyst of Comparative Example 1, and the catalyst of Example 1 was superior to other catalysts in terms of denitrification performance. In addition, it was confirmed that the catalyst of Example 4 exhibited similar denitrification performance to the catalyst of Comparative Example 1, despite the amount of vanadium and tungsten supported by half of the catalyst of Comparative Example 1.

[ Experimental Example  3]: For Selective Catalytic Reduction Reaction Of the denitration catalyst Specific surface area  Measure

The specific surface area (S _BET ), average pore size and pore volume of the NO x removal catalysts prepared in Examples 1 to 4 and Comparative Example 1 were measured by ASAP 2010 (Micrometritics Co., USA). The results are shown in Table 3.

division S _BET (m ² g ^-1 ) pore volume (cm ³ g ^-1 ) average pore size (nm) Example 1 74.29 0.33 16.33 Example 2 75.92 0.34 15.94 Example 3 77.31 0.29 13.70 Example 4 78.96 0.31 13.95 Comparative Example 1 50.13 0.31 22.38

As shown in Table 3, the catalysts of Examples 1 to 4 showed larger specific surface area than the catalyst of Comparative Example 1. This is because graphene having a large specific surface area is used as a support for a catalytically active substance.

[ Experimental Example  4]: for selective catalytic reduction reaction Of the denitration catalyst TEM  Measure

The denitration catalysts for the selective catalytic reduction reaction prepared in Example 1 and Comparative Example 1 were measured through a TEM (transmission electron microscope, JEM-2100F, JEOL) 3.

As shown in Fig. 3, it was confirmed that the catalyst prepared in Comparative Example 1 (Fig. 3 (b)) was in the state of aggregation, whereas in the case of the catalyst prepared in Example 1 (Fig. 3 Was uniformly dispersed on the surface of the graphene.

Catalysts are mainly surface reactions that lower the activation energy required for the reaction and control the reaction rate in the chemical reaction. In the NO x removal catalyst for selective catalytic reduction, the reaction rate is controlled by the active component present on the surface of the catalyst, so that high specific surface area and dispersibility of the catalytically active substance are important. Thus, it is understood that the denitration catalyst for the selective catalytic reduction reaction according to the present invention has an effect on the enhanced activity of the catalyst having the active material on the graphene due to its high specific surface area and dispersibility.

[ Experimental Example  5]: for selective catalytic reduction reaction Of the denitration catalyst  ammonia Temperature desorption method  Active acid point measurement

NH ₃ -TPD ( NH ₃ - Temperature Programmed Desorption) reactor was charged with the catalyst prepared in Example 1 and Comparative Example 1, NH ₃ gas was introduced at room temperature for one hour to adsorb NH ₃ on the surface of the catalyst The post catalyst was purged, and NH ₃ desorption amount according to the temperature was analyzed by a mass analyzer (Autochem II 2920, Micromeritics). The results are shown in FIG.

As shown in FIG. 4, it can be seen that the denitration catalyst for the selective catalytic reduction reaction of Example 1 has a higher desorption amount of NH ₃ than the catalyst of Comparative Example 1 in the whole analysis temperature range. This means that the acid value of the catalyst of Example 2 is higher than that of the catalyst of Comparative Example 1, so that NH ₃ is more adsorbed. As a result, an increase in the adsorption amount of NH ₃ results in an effect of improving the denitration rate.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (6)

(a) preparing an aqueous metal precursor solution by mixing a vanadium precursor aqueous solution, a tungsten precursor aqueous solution, and a titanium precursor aqueous solution;
(b) impregnating the metal precursor aqueous solution with graphene oxide or reduced graphene oxide to obtain an impregnated product; And
(c) drying the impregnated material and then calcining the impregnated material.
The method according to claim 1,
Wherein the metal precursor aqueous solution of step (a) comprises 0.1 to 3 parts by weight of a vanadium precursor and 1 to 10 parts by weight of a tungsten precursor based on 100 parts by weight of the titanium precursor. &Lt; / RTI &gt;
The method according to claim 1,
Wherein the content of graphene oxide or reduced graphene oxide in step (b) is 5 parts by weight to 15 parts by weight based on 100 parts by weight of the titanium precursor.
Wherein the catalytically active vanadium oxide, tungsten oxide, and titanium oxide are supported on graphene oxide or reduced graphene oxide as a catalyst support.
5. The method of claim 4,
Wherein the denitration catalyst for selective catalytic reduction comprises 0.1 to 3 parts by weight of vanadium oxide and 1.0 to 10 parts by weight of tungsten oxide per 100 parts by weight of titanium oxide.
5. The method of claim 4,
Wherein the denitration catalyst for selective catalytic reduction reaction comprises 5 to 15 parts by weight of graphene oxide or reduced graphene oxide per 100 parts by weight of titanium oxide.

Images